diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8e9253304..7c4b83697 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,15 @@
 
 [1]: https://www.npmjs.com/package/@google-cloud/firestore?activeTab=versions
 
+## [6.6.0](https://github.com/googleapis/nodejs-firestore/compare/v6.5.0...v6.6.0) (2023-05-18)
+
+
+### Features
+
+* Add ApiScope and COLLECTION_RECURSIVE query_scope for Firestore index ([#1849](https://github.com/googleapis/nodejs-firestore/issues/1849)) ([b671452](https://github.com/googleapis/nodejs-firestore/commit/b6714528956f3907b1ca4aded372592ef00d34d6))
+* Add bloom filter related proto fields ([#1843](https://github.com/googleapis/nodejs-firestore/issues/1843)) ([b64e0c1](https://github.com/googleapis/nodejs-firestore/commit/b64e0c15d0f824a688ff42a8ad940b520f87cf9b))
+* Add support for environment variable FIRESTORE_PREFER_REST ([#1848](https://github.com/googleapis/nodejs-firestore/issues/1848)) ([96b1d2a](https://github.com/googleapis/nodejs-firestore/commit/96b1d2ab3248f6c4bb70d1cf735aea827a2a13da))
+
 ## [6.5.0](https://github.com/googleapis/nodejs-firestore/compare/v6.4.3...v6.5.0) (2023-03-06)
 
 
diff --git a/dev/protos/google/api/client.proto b/dev/protos/google/api/client.proto
index 227ccf3a5..6d01954ee 100644
--- a/dev/protos/google/api/client.proto
+++ b/dev/protos/google/api/client.proto
@@ -1,4 +1,4 @@
-// Copyright 2018 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -112,7 +112,9 @@ message CommonLanguageSettings {
 
 // Details about how and where to publish client libraries.
 message ClientLibrarySettings {
-  // Version of the API to apply these settings to.
+  // Version of the API to apply these settings to. This is the full protobuf
+  // package for the API, ending in the version element.
+  // Examples: "google.cloud.speech.v1" and "google.spanner.admin.database.v1".
   string version = 1;
 
   // Launch stage of this version of the API.
@@ -155,7 +157,7 @@ message Publishing {
   // long-running operation pattern.
   repeated MethodSettings method_settings = 2;
 
-  // Link to a place that API users can report issues.  Example:
+  // Link to a *public* URI where users can report issues.  Example:
   // https://issuetracker.google.com/issues/new?component=190865&template=1161103
   string new_issue_uri = 101;
 
@@ -186,6 +188,10 @@ message Publishing {
   // times in this list, then the last one wins.  Settings from earlier
   // settings with the same version string are discarded.
   repeated ClientLibrarySettings library_settings = 109;
+
+  // Optional link to proto reference documentation.  Example:
+  // https://cloud.google.com/pubsub/lite/docs/reference/rpc
+  string proto_reference_documentation_uri = 110;
 }
 
 // Settings for Java client libraries.
@@ -251,6 +257,36 @@ message NodeSettings {
 message DotnetSettings {
   // Some settings.
   CommonLanguageSettings common = 1;
+
+  // Map from original service names to renamed versions.
+  // This is used when the default generated types
+  // would cause a naming conflict. (Neither name is
+  // fully-qualified.)
+  // Example: Subscriber to SubscriberServiceApi.
+  map<string, string> renamed_services = 2;
+
+  // Map from full resource types to the effective short name
+  // for the resource. This is used when otherwise resource
+  // named from different services would cause naming collisions.
+  // Example entry:
+  // "datalabeling.googleapis.com/Dataset": "DataLabelingDataset"
+  map<string, string> renamed_resources = 3;
+
+  // List of full resource types to ignore during generation.
+  // This is typically used for API-specific Location resources,
+  // which should be handled by the generator as if they were actually
+  // the common Location resources.
+  // Example entry: "documentai.googleapis.com/Location"
+  repeated string ignored_resources = 4;
+
+  // Namespaces which must be aliased in snippets due to
+  // a known (but non-generator-predictable) naming collision
+  repeated string forced_namespace_aliases = 5;
+
+  // Method signatures (in the form "service.method(signature)")
+  // which are provided separately, so shouldn't be generated.
+  // Snippets *calling* these methods are still generated, however.
+  repeated string handwritten_signatures = 6;
 }
 
 // Settings for Ruby client libraries.
@@ -302,8 +338,8 @@ message MethodSettings {
   // Example of a YAML configuration::
   //
   //  publishing:
-  //    method_behavior:
-  //      - selector: CreateAdDomain
+  //    method_settings:
+  //      - selector: google.cloud.speech.v2.Speech.BatchRecognize
   //        long_running:
   //          initial_poll_delay:
   //            seconds: 60 # 1 minute
@@ -332,6 +368,15 @@ enum ClientLibraryOrganization {
 
   // Street View Org.
   STREET_VIEW = 4;
+
+  // Shopping Org.
+  SHOPPING = 5;
+
+  // Geo Org.
+  GEO = 6;
+
+  // Generative AI - https://developers.generativeai.google
+  GENERATIVE_AI = 7;
 }
 
 // To where should client libraries be published?
diff --git a/dev/protos/google/api/field_behavior.proto b/dev/protos/google/api/field_behavior.proto
index c4abe3b67..1a3a2f2fb 100644
--- a/dev/protos/google/api/field_behavior.proto
+++ b/dev/protos/google/api/field_behavior.proto
@@ -1,4 +1,4 @@
-// Copyright 2018 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/dev/protos/google/api/http.proto b/dev/protos/google/api/http.proto
index 113fa936a..31d867a27 100644
--- a/dev/protos/google/api/http.proto
+++ b/dev/protos/google/api/http.proto
@@ -1,4 +1,4 @@
-// Copyright 2015 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -210,15 +210,18 @@ message Http {
 // 1. Leaf request fields (recursive expansion nested messages in the request
 //    message) are classified into three categories:
 //    - Fields referred by the path template. They are passed via the URL path.
-//    - Fields referred by the [HttpRule.body][google.api.HttpRule.body]. They are passed via the HTTP
+//    - Fields referred by the [HttpRule.body][google.api.HttpRule.body]. They
+//    are passed via the HTTP
 //      request body.
 //    - All other fields are passed via the URL query parameters, and the
 //      parameter name is the field path in the request message. A repeated
 //      field can be represented as multiple query parameters under the same
 //      name.
-//  2. If [HttpRule.body][google.api.HttpRule.body] is "*", there is no URL query parameter, all fields
+//  2. If [HttpRule.body][google.api.HttpRule.body] is "*", there is no URL
+//  query parameter, all fields
 //     are passed via URL path and HTTP request body.
-//  3. If [HttpRule.body][google.api.HttpRule.body] is omitted, there is no HTTP request body, all
+//  3. If [HttpRule.body][google.api.HttpRule.body] is omitted, there is no HTTP
+//  request body, all
 //     fields are passed via URL path and URL query parameters.
 //
 // ### Path template syntax
@@ -313,7 +316,8 @@ message Http {
 message HttpRule {
   // Selects a method to which this rule applies.
   //
-  // Refer to [selector][google.api.DocumentationRule.selector] for syntax details.
+  // Refer to [selector][google.api.DocumentationRule.selector] for syntax
+  // details.
   string selector = 1;
 
   // Determines the URL pattern is matched by this rules. This pattern can be
diff --git a/dev/protos/google/api/launch_stage.proto b/dev/protos/google/api/launch_stage.proto
index 6524db575..9802de795 100644
--- a/dev/protos/google/api/launch_stage.proto
+++ b/dev/protos/google/api/launch_stage.proto
@@ -1,4 +1,4 @@
-// Copyright 2015 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/dev/protos/google/api/resource.proto b/dev/protos/google/api/resource.proto
index 0ce0344f5..bf0cbec5d 100644
--- a/dev/protos/google/api/resource.proto
+++ b/dev/protos/google/api/resource.proto
@@ -1,4 +1,4 @@
-// Copyright 2018 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/dev/protos/google/firestore/admin/v1/database.proto b/dev/protos/google/firestore/admin/v1/database.proto
index 3f242c3e1..5d9b762a1 100644
--- a/dev/protos/google/firestore/admin/v1/database.proto
+++ b/dev/protos/google/firestore/admin/v1/database.proto
@@ -20,7 +20,7 @@ import "google/api/field_behavior.proto";
 import "google/api/resource.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.Admin.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/admin/v1;admin";
+option go_package = "cloud.google.com/go/firestore/apiv1/admin/adminpb;adminpb";
 option java_multiple_files = true;
 option java_outer_classname = "DatabaseProto";
 option java_package = "com.google.firestore.admin.v1";
diff --git a/dev/protos/google/firestore/admin/v1/field.proto b/dev/protos/google/firestore/admin/v1/field.proto
index 0bbb11d8a..5cd1cd481 100644
--- a/dev/protos/google/firestore/admin/v1/field.proto
+++ b/dev/protos/google/firestore/admin/v1/field.proto
@@ -21,7 +21,7 @@ import "google/api/resource.proto";
 import "google/firestore/admin/v1/index.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.Admin.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/admin/v1;admin";
+option go_package = "cloud.google.com/go/firestore/apiv1/admin/adminpb;adminpb";
 option java_multiple_files = true;
 option java_outer_classname = "FieldProto";
 option java_package = "com.google.firestore.admin.v1";
diff --git a/dev/protos/google/firestore/admin/v1/firestore_admin.proto b/dev/protos/google/firestore/admin/v1/firestore_admin.proto
index c493673ae..71f849d0b 100644
--- a/dev/protos/google/firestore/admin/v1/firestore_admin.proto
+++ b/dev/protos/google/firestore/admin/v1/firestore_admin.proto
@@ -28,7 +28,7 @@ import "google/protobuf/empty.proto";
 import "google/protobuf/field_mask.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.Admin.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/admin/v1;admin";
+option go_package = "cloud.google.com/go/firestore/apiv1/admin/adminpb;adminpb";
 option java_multiple_files = true;
 option java_outer_classname = "FirestoreAdminProto";
 option java_package = "com.google.firestore.admin.v1";
diff --git a/dev/protos/google/firestore/admin/v1/index.proto b/dev/protos/google/firestore/admin/v1/index.proto
index 066d4109f..2567da650 100644
--- a/dev/protos/google/firestore/admin/v1/index.proto
+++ b/dev/protos/google/firestore/admin/v1/index.proto
@@ -1,4 +1,4 @@
-// Copyright 2022 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package google.firestore.admin.v1;
 import "google/api/resource.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.Admin.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/admin/v1;admin";
+option go_package = "cloud.google.com/go/firestore/apiv1/admin/adminpb;adminpb";
 option java_multiple_files = true;
 option java_outer_classname = "IndexProto";
 option java_package = "com.google.firestore.admin.v1";
@@ -50,6 +50,21 @@ message Index {
     // against all collections that has the collection id specified by the
     // index.
     COLLECTION_GROUP = 2;
+
+    // Include all the collections's ancestor in the index. Only available for
+    // Datastore Mode databases.
+    COLLECTION_RECURSIVE = 3;
+  }
+
+  // API Scope defines the APIs (Firestore Native, or Firestore in
+  // Datastore Mode) that are supported for queries.
+  enum ApiScope {
+    // The index can only be used by the Firestore Native query API.
+    // This is the default.
+    ANY_API = 0;
+
+    // The index can only be used by the Firestore in Datastore Mode query API.
+    DATASTORE_MODE_API = 1;
   }
 
   // A field in an index.
@@ -138,14 +153,17 @@ message Index {
   // time, and that have the same collection id as this index.
   QueryScope query_scope = 2;
 
+  // The API scope supported by this index.
+  ApiScope api_scope = 5;
+
   // The fields supported by this index.
   //
-  // For composite indexes, this is always 2 or more fields.
-  // The last field entry is always for the field path `__name__`. If, on
-  // creation, `__name__` was not specified as the last field, it will be added
-  // automatically with the same direction as that of the last field defined. If
-  // the final field in a composite index is not directional, the `__name__`
-  // will be ordered ASCENDING (unless explicitly specified).
+  // For composite indexes, this requires a minimum of 2 and a maximum of 100
+  // fields. The last field entry is always for the field path `__name__`. If,
+  // on creation, `__name__` was not specified as the last field, it will be
+  // added automatically with the same direction as that of the last field
+  // defined. If the final field in a composite index is not directional, the
+  // `__name__` will be ordered ASCENDING (unless explicitly specified).
   //
   // For single field indexes, this will always be exactly one entry with a
   // field path equal to the field path of the associated field.
diff --git a/dev/protos/google/firestore/admin/v1/location.proto b/dev/protos/google/firestore/admin/v1/location.proto
index 8f7519c4d..abf836d92 100644
--- a/dev/protos/google/firestore/admin/v1/location.proto
+++ b/dev/protos/google/firestore/admin/v1/location.proto
@@ -17,7 +17,7 @@ syntax = "proto3";
 package google.firestore.admin.v1;
 
 option csharp_namespace = "Google.Cloud.Firestore.Admin.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/admin/v1;admin";
+option go_package = "cloud.google.com/go/firestore/apiv1/admin/adminpb;adminpb";
 option java_multiple_files = true;
 option java_outer_classname = "LocationProto";
 option java_package = "com.google.firestore.admin.v1";
diff --git a/dev/protos/google/firestore/admin/v1/operation.proto b/dev/protos/google/firestore/admin/v1/operation.proto
index 654a6ad6c..6b0562293 100644
--- a/dev/protos/google/firestore/admin/v1/operation.proto
+++ b/dev/protos/google/firestore/admin/v1/operation.proto
@@ -20,7 +20,7 @@ import "google/firestore/admin/v1/index.proto";
 import "google/protobuf/timestamp.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.Admin.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/admin/v1;admin";
+option go_package = "cloud.google.com/go/firestore/apiv1/admin/adminpb;adminpb";
 option java_multiple_files = true;
 option java_outer_classname = "OperationProto";
 option java_package = "com.google.firestore.admin.v1";
diff --git a/dev/protos/google/firestore/v1/aggregation_result.proto b/dev/protos/google/firestore/v1/aggregation_result.proto
index dc0d172a2..05fea5da9 100644
--- a/dev/protos/google/firestore/v1/aggregation_result.proto
+++ b/dev/protos/google/firestore/v1/aggregation_result.proto
@@ -1,4 +1,4 @@
-// Copyright 2022 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package google.firestore.v1;
 import "google/firestore/v1/document.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "AggregationResultProto";
 option java_package = "com.google.firestore.v1";
diff --git a/dev/protos/google/firestore/v1/bloom_filter.proto b/dev/protos/google/firestore/v1/bloom_filter.proto
new file mode 100644
index 000000000..c00bb9c17
--- /dev/null
+++ b/dev/protos/google/firestore/v1/bloom_filter.proto
@@ -0,0 +1,73 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.firestore.v1;
+
+option csharp_namespace = "Google.Cloud.Firestore.V1";
+option go_package = "cloud.google.com/go/firestore/apiv1/firestorepb;firestorepb";
+option java_multiple_files = true;
+option java_outer_classname = "BloomFilterProto";
+option java_package = "com.google.firestore.v1";
+option objc_class_prefix = "GCFS";
+option php_namespace = "Google\\Cloud\\Firestore\\V1";
+option ruby_package = "Google::Cloud::Firestore::V1";
+
+// A sequence of bits, encoded in a byte array.
+//
+// Each byte in the `bitmap` byte array stores 8 bits of the sequence. The only
+// exception is the last byte, which may store 8 _or fewer_ bits. The `padding`
+// defines the number of bits of the last byte to be ignored as "padding". The
+// values of these "padding" bits are unspecified and must be ignored.
+//
+// To retrieve the first bit, bit 0, calculate: `(bitmap[0] & 0x01) != 0`.
+// To retrieve the second bit, bit 1, calculate: `(bitmap[0] & 0x02) != 0`.
+// To retrieve the third bit, bit 2, calculate: `(bitmap[0] & 0x04) != 0`.
+// To retrieve the fourth bit, bit 3, calculate: `(bitmap[0] & 0x08) != 0`.
+// To retrieve bit n, calculate: `(bitmap[n / 8] & (0x01 << (n % 8))) != 0`.
+//
+// The "size" of a `BitSequence` (the number of bits it contains) is calculated
+// by this formula: `(bitmap.length * 8) - padding`.
+message BitSequence {
+  // The bytes that encode the bit sequence.
+  // May have a length of zero.
+  bytes bitmap = 1;
+
+  // The number of bits of the last byte in `bitmap` to ignore as "padding".
+  // If the length of `bitmap` is zero, then this value must be `0`.
+  // Otherwise, this value must be between 0 and 7, inclusive.
+  int32 padding = 2;
+}
+
+// A bloom filter (https://en.wikipedia.org/wiki/Bloom_filter).
+//
+// The bloom filter hashes the entries with MD5 and treats the resulting 128-bit
+// hash as 2 distinct 64-bit hash values, interpreted as unsigned integers
+// using 2's complement encoding.
+//
+// These two hash values, named `h1` and `h2`, are then used to compute the
+// `hash_count` hash values using the formula, starting at `i=0`:
+//
+//     h(i) = h1 + (i * h2)
+//
+// These resulting values are then taken modulo the number of bits in the bloom
+// filter to get the bits of the bloom filter to test for the given entry.
+message BloomFilter {
+  // The bloom filter data.
+  BitSequence bits = 1;
+
+  // The number of hashes used by the algorithm.
+  int32 hash_count = 2;
+}
diff --git a/dev/protos/google/firestore/v1/common.proto b/dev/protos/google/firestore/v1/common.proto
index c1bd92d8f..29cde08d3 100644
--- a/dev/protos/google/firestore/v1/common.proto
+++ b/dev/protos/google/firestore/v1/common.proto
@@ -1,4 +1,4 @@
-// Copyright 2022 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package google.firestore.v1;
 import "google/protobuf/timestamp.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "CommonProto";
 option java_package = "com.google.firestore.v1";
diff --git a/dev/protos/google/firestore/v1/document.proto b/dev/protos/google/firestore/v1/document.proto
index 41283588e..795200498 100644
--- a/dev/protos/google/firestore/v1/document.proto
+++ b/dev/protos/google/firestore/v1/document.proto
@@ -1,4 +1,4 @@
-// Copyright 2022 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -21,7 +21,7 @@ import "google/protobuf/timestamp.proto";
 import "google/type/latlng.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "DocumentProto";
 option java_package = "com.google.firestore.v1";
diff --git a/dev/protos/google/firestore/v1/firestore.proto b/dev/protos/google/firestore/v1/firestore.proto
index b62bf64e5..c6f7b921c 100644
--- a/dev/protos/google/firestore/v1/firestore.proto
+++ b/dev/protos/google/firestore/v1/firestore.proto
@@ -1,4 +1,4 @@
-// Copyright 2022 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -26,10 +26,11 @@ import "google/firestore/v1/query.proto";
 import "google/firestore/v1/write.proto";
 import "google/protobuf/empty.proto";
 import "google/protobuf/timestamp.proto";
+import "google/protobuf/wrappers.proto";
 import "google/rpc/status.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "FirestoreProto";
 option java_package = "com.google.firestore.v1";
@@ -178,7 +179,7 @@ service Firestore {
   }
 
   // Streams batches of document updates and deletes, in order. This method is
-  // only available via the gRPC API (not REST).
+  // only available via gRPC or WebChannel (not REST).
   rpc Write(stream WriteRequest) returns (stream WriteResponse) {
     option (google.api.http) = {
       post: "/v1/{database=projects/*/databases/*}/documents:write"
@@ -186,8 +187,8 @@ service Firestore {
     };
   }
 
-  // Listens to changes. This method is only available via the gRPC API (not
-  // REST).
+  // Listens to changes. This method is only available via gRPC or WebChannel
+  // (not REST).
   rpc Listen(stream ListenRequest) returns (stream ListenResponse) {
     option (google.api.http) = {
       post: "/v1/{database=projects/*/databases/*}/documents:listen"
@@ -655,7 +656,14 @@ message RunAggregationQueryResponse {
   // a new transaction.
   bytes transaction = 2;
 
-  // The time at which the aggregate value is valid for.
+  // The time at which the aggregate result was computed. This is always
+  // monotonically increasing; in this case, the previous AggregationResult in
+  // the result stream are guaranteed not to have changed between their
+  // `read_time` and this one.
+  //
+  // If the query returns no results, a response with `read_time` and no
+  // `result` will be sent, and this represents the time at which the query
+  // was run.
   google.protobuf.Timestamp read_time = 3;
 }
 
@@ -925,6 +933,14 @@ message Target {
 
   // If the target should be removed once it is current and consistent.
   bool once = 6;
+
+  // The number of documents that last matched the query at the resume token or
+  // read time.
+  //
+  // This value is only relevant when a `resume_type` is provided. This value
+  // being present and greater than zero signals that the client wants
+  // `ExistenceFilter.unchanged_names` to be included in the response.
+  google.protobuf.Int32Value expected_count = 12;
 }
 
 // Targets being watched have changed.
diff --git a/dev/protos/google/firestore/v1/query.proto b/dev/protos/google/firestore/v1/query.proto
index 6d8ffce80..8f89c48d9 100644
--- a/dev/protos/google/firestore/v1/query.proto
+++ b/dev/protos/google/firestore/v1/query.proto
@@ -1,4 +1,4 @@
-// Copyright 2022 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -21,7 +21,7 @@ import "google/firestore/v1/document.proto";
 import "google/protobuf/wrappers.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "QueryProto";
 option java_package = "com.google.firestore.v1";
@@ -136,8 +136,9 @@ message StructuredQuery {
       //
       // Requires:
       //
-      // * That `value` is a non-empty `ArrayValue` with at most 10 values.
-      // * No other `IN` or `ARRAY_CONTAINS_ANY` or `NOT_IN`.
+      // * That `value` is a non-empty `ArrayValue`, subject to disjunction
+      //   limits.
+      // * No `NOT_IN` filters in the same query.
       IN = 8;
 
       // The given `field` is an array that contains any of the values in the
@@ -145,8 +146,10 @@ message StructuredQuery {
       //
       // Requires:
       //
-      // * That `value` is a non-empty `ArrayValue` with at most 10 values.
-      // * No other `IN` or `ARRAY_CONTAINS_ANY` or `NOT_IN`.
+      // * That `value` is a non-empty `ArrayValue`, subject to disjunction
+      //   limits.
+      // * No other `ARRAY_CONTAINS_ANY` filters within the same disjunction.
+      // * No `NOT_IN` filters in the same query.
       ARRAY_CONTAINS_ANY = 9;
 
       // The value of the `field` is not in the given array.
@@ -154,7 +157,7 @@ message StructuredQuery {
       // Requires:
       //
       // * That `value` is a non-empty `ArrayValue` with at most 10 values.
-      // * No other `IN`, `ARRAY_CONTAINS_ANY`, `NOT_IN`, `NOT_EQUAL`,
+      // * No other `OR`, `IN`, `ARRAY_CONTAINS_ANY`, `NOT_IN`, `NOT_EQUAL`,
       //   `IS_NOT_NULL`, or `IS_NOT_NAN`.
       // * That `field` comes first in the `order_by`.
       NOT_IN = 10;
@@ -251,7 +254,11 @@ message StructuredQuery {
     repeated FieldReference fields = 2;
   }
 
-  // The projection to return.
+  // Optional sub-set of the fields to return.
+  //
+  // This acts as a [DocumentMask][google.firestore.v1.DocumentMask] over the
+  // documents returned from a query. When not set, assumes that the caller
+  // wants all fields returned.
   Projection select = 1;
 
   // The collections to query.
@@ -349,7 +356,7 @@ message StructuredQuery {
 // Firestore query for running an aggregation over a
 // [StructuredQuery][google.firestore.v1.StructuredQuery].
 message StructuredAggregationQuery {
-  // Defines a aggregation that produces a single result.
+  // Defines an aggregation that produces a single result.
   message Aggregation {
     // Count of documents that match the query.
     //
@@ -360,7 +367,7 @@ message StructuredAggregationQuery {
       // count.
       //
       // This provides a way to set an upper bound on the number of documents
-      // to scan, limiting latency and cost.
+      // to scan, limiting latency, and cost.
       //
       // Unspecified is interpreted as no bound.
       //
@@ -394,7 +401,7 @@ message StructuredAggregationQuery {
     //   COUNT_UP_TO(1) AS count_up_to_1,
     //   COUNT_UP_TO(2),
     //   COUNT_UP_TO(3) AS count_up_to_3,
-    //   COUNT_UP_TO(4)
+    //   COUNT(*)
     // OVER (
     //   ...
     // );
@@ -407,7 +414,7 @@ message StructuredAggregationQuery {
     //   COUNT_UP_TO(1) AS count_up_to_1,
     //   COUNT_UP_TO(2) AS field_1,
     //   COUNT_UP_TO(3) AS count_up_to_3,
-    //   COUNT_UP_TO(4) AS field_2
+    //   COUNT(*) AS field_2
     // OVER (
     //   ...
     // );
diff --git a/dev/protos/google/firestore/v1/write.proto b/dev/protos/google/firestore/v1/write.proto
index 3cc3b8429..4ed0f5475 100644
--- a/dev/protos/google/firestore/v1/write.proto
+++ b/dev/protos/google/firestore/v1/write.proto
@@ -1,4 +1,4 @@
-// Copyright 2022 Google LLC
+// Copyright 2023 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -16,12 +16,13 @@ syntax = "proto3";
 
 package google.firestore.v1;
 
+import "google/firestore/v1/bloom_filter.proto";
 import "google/firestore/v1/common.proto";
 import "google/firestore/v1/document.proto";
 import "google/protobuf/timestamp.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "WriteProto";
 option java_package = "com.google.firestore.v1";
@@ -264,4 +265,19 @@ message ExistenceFilter {
   // If different from the count of documents in the client that match, the
   // client must manually determine which documents no longer match the target.
   int32 count = 2;
+
+  // A bloom filter that contains the UTF-8 byte encodings of the resource names
+  // of the documents that match
+  // [target_id][google.firestore.v1.ExistenceFilter.target_id], in the form
+  // `projects/{project_id}/databases/{database_id}/documents/{document_path}`
+  // that have NOT changed since the query results indicated by the resume token
+  // or timestamp given in `Target.resume_type`.
+  //
+  // This bloom filter may be omitted at the server's discretion, such as if it
+  // is deemed that the client will not make use of it or if it is too
+  // computationally expensive to calculate or transmit. Clients must gracefully
+  // handle this field being absent by falling back to the logic used before
+  // this field existed; that is, re-add the target without a resume token to
+  // figure out which documents in the client's cache are out of sync.
+  BloomFilter unchanged_names = 3;
 }
diff --git a/dev/protos/google/firestore/v1beta1/common.proto b/dev/protos/google/firestore/v1beta1/common.proto
index af26d0b6f..1a18c41bc 100644
--- a/dev/protos/google/firestore/v1beta1/common.proto
+++ b/dev/protos/google/firestore/v1beta1/common.proto
@@ -19,7 +19,7 @@ package google.firestore.v1beta1;
 import "google/protobuf/timestamp.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1Beta1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1beta1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1beta1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "CommonProto";
 option java_package = "com.google.firestore.v1beta1";
diff --git a/dev/protos/google/firestore/v1beta1/document.proto b/dev/protos/google/firestore/v1beta1/document.proto
index e425cd6e8..de192806d 100644
--- a/dev/protos/google/firestore/v1beta1/document.proto
+++ b/dev/protos/google/firestore/v1beta1/document.proto
@@ -21,7 +21,7 @@ import "google/protobuf/timestamp.proto";
 import "google/type/latlng.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1Beta1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1beta1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1beta1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "DocumentProto";
 option java_package = "com.google.firestore.v1beta1";
diff --git a/dev/protos/google/firestore/v1beta1/firestore.proto b/dev/protos/google/firestore/v1beta1/firestore.proto
index 1fd3a58f3..047f029e4 100644
--- a/dev/protos/google/firestore/v1beta1/firestore.proto
+++ b/dev/protos/google/firestore/v1beta1/firestore.proto
@@ -28,7 +28,7 @@ import "google/protobuf/timestamp.proto";
 import "google/rpc/status.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1Beta1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1beta1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1beta1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "FirestoreProto";
 option java_package = "com.google.firestore.v1beta1";
diff --git a/dev/protos/google/firestore/v1beta1/query.proto b/dev/protos/google/firestore/v1beta1/query.proto
index cfb5401e1..7d7ef11ce 100644
--- a/dev/protos/google/firestore/v1beta1/query.proto
+++ b/dev/protos/google/firestore/v1beta1/query.proto
@@ -20,7 +20,7 @@ import "google/firestore/v1beta1/document.proto";
 import "google/protobuf/wrappers.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1Beta1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1beta1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1beta1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "QueryProto";
 option java_package = "com.google.firestore.v1beta1";
diff --git a/dev/protos/google/firestore/v1beta1/write.proto b/dev/protos/google/firestore/v1beta1/write.proto
index 3fd1b5965..124526a59 100644
--- a/dev/protos/google/firestore/v1beta1/write.proto
+++ b/dev/protos/google/firestore/v1beta1/write.proto
@@ -21,7 +21,7 @@ import "google/firestore/v1beta1/document.proto";
 import "google/protobuf/timestamp.proto";
 
 option csharp_namespace = "Google.Cloud.Firestore.V1Beta1";
-option go_package = "google.golang.org/genproto/googleapis/firestore/v1beta1;firestore";
+option go_package = "cloud.google.com/go/firestore/apiv1beta1/firestorepb;firestorepb";
 option java_multiple_files = true;
 option java_outer_classname = "WriteProto";
 option java_package = "com.google.firestore.v1beta1";
diff --git a/dev/protos/google/longrunning/operations.proto b/dev/protos/google/longrunning/operations.proto
index c1fdc6f52..c8fda207e 100644
--- a/dev/protos/google/longrunning/operations.proto
+++ b/dev/protos/google/longrunning/operations.proto
@@ -26,7 +26,7 @@ import "google/protobuf/descriptor.proto";
 
 option cc_enable_arenas = true;
 option csharp_namespace = "Google.LongRunning";
-option go_package = "google.golang.org/genproto/googleapis/longrunning;longrunning";
+option go_package = "cloud.google.com/go/longrunning/autogen/longrunningpb;longrunningpb";
 option java_multiple_files = true;
 option java_outer_classname = "OperationsProto";
 option java_package = "com.google.longrunning";
diff --git a/dev/protos/google/protobuf/any.proto b/dev/protos/google/protobuf/any.proto
index 561da0cb1..eff44e509 100644
--- a/dev/protos/google/protobuf/any.proto
+++ b/dev/protos/google/protobuf/any.proto
@@ -68,7 +68,7 @@ option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 //       foo = any.unpack(Foo.getDefaultInstance());
 //     }
 //
-// Example 3: Pack and unpack a message in Python.
+//  Example 3: Pack and unpack a message in Python.
 //
 //     foo = Foo(...)
 //     any = Any()
@@ -78,7 +78,7 @@ option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 //       any.Unpack(foo)
 //       ...
 //
-// Example 4: Pack and unpack a message in Go
+//  Example 4: Pack and unpack a message in Go
 //
 //      foo := &pb.Foo{...}
 //      any, err := anypb.New(foo)
@@ -98,7 +98,7 @@ option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 // name "y.z".
 //
 // JSON
-//
+// ====
 // The JSON representation of an `Any` value uses the regular
 // representation of the deserialized, embedded message, with an
 // additional field `@type` which contains the type URL. Example:
@@ -149,7 +149,8 @@ message Any {
   //
   // Note: this functionality is not currently available in the official
   // protobuf release, and it is not used for type URLs beginning with
-  // type.googleapis.com.
+  // type.googleapis.com. As of May 2023, there are no widely used type server
+  // implementations and no plans to implement one.
   //
   // Schemes other than `http`, `https` (or the empty scheme) might be
   // used with implementation specific semantics.
diff --git a/dev/protos/google/protobuf/descriptor.proto b/dev/protos/google/protobuf/descriptor.proto
index 3b3867543..c994d4a7b 100644
--- a/dev/protos/google/protobuf/descriptor.proto
+++ b/dev/protos/google/protobuf/descriptor.proto
@@ -133,6 +133,49 @@ message ExtensionRangeOptions {
   // The parser stores options it doesn't recognize here. See above.
   repeated UninterpretedOption uninterpreted_option = 999;
 
+  message Declaration {
+    // The extension number declared within the extension range.
+    optional int32 number = 1;
+
+    // The fully-qualified name of the extension field. There must be a leading
+    // dot in front of the full name.
+    optional string full_name = 2;
+
+    // The fully-qualified type name of the extension field. Unlike
+    // Metadata.type, Declaration.type must have a leading dot for messages
+    // and enums.
+    optional string type = 3;
+
+    // Deprecated. Please use "repeated".
+    optional bool is_repeated = 4 [deprecated = true];
+
+    // If true, indicates that the number is reserved in the extension range,
+    // and any extension field with the number will fail to compile. Set this
+    // when a declared extension field is deleted.
+    optional bool reserved = 5;
+
+    // If true, indicates that the extension must be defined as repeated.
+    // Otherwise the extension must be defined as optional.
+    optional bool repeated = 6;
+  }
+
+  // For external users: DO NOT USE. We are in the process of open sourcing
+  // extension declaration and executing internal cleanups before it can be
+  // used externally.
+  repeated Declaration declaration = 2 [retention = RETENTION_SOURCE];
+
+  // The verification state of the extension range.
+  enum VerificationState {
+    // All the extensions of the range must be declared.
+    DECLARATION = 0;
+    UNVERIFIED = 1;
+  }
+
+  // The verification state of the range.
+  // TODO(b/278783756): flip the default to DECLARATION once all empty ranges
+  // are marked as UNVERIFIED.
+  optional VerificationState verification = 3 [default = UNVERIFIED];
+
   // Clients can define custom options in extensions of this message. See above.
   extensions 1000 to max;
 }
@@ -540,13 +583,21 @@ message MessageOptions {
 message FieldOptions {
   // The ctype option instructs the C++ code generator to use a different
   // representation of the field than it normally would.  See the specific
-  // options below.  This option is not yet implemented in the open source
-  // release -- sorry, we'll try to include it in a future version!
+  // options below.  This option is only implemented to support use of
+  // [ctype=CORD] and [ctype=STRING] (the default) on non-repeated fields of
+  // type "bytes" in the open source release -- sorry, we'll try to include
+  // other types in a future version!
   optional CType ctype = 1 [default = STRING];
   enum CType {
     // Default mode.
     STRING = 0;
 
+    // The option [ctype=CORD] may be applied to a non-repeated field of type
+    // "bytes". It indicates that in C++, the data should be stored in a Cord
+    // instead of a string.  For very large strings, this may reduce memory
+    // fragmentation. It may also allow better performance when parsing from a
+    // Cord, or when parsing with aliasing enabled, as the parsed Cord may then
+    // alias the original buffer.
     CORD = 1;
 
     STRING_PIECE = 2;
@@ -659,7 +710,7 @@ message FieldOptions {
     TARGET_TYPE_METHOD = 9;
   }
 
-  optional OptionTargetType target = 18;
+  repeated OptionTargetType targets = 19;
 
   // The parser stores options it doesn't recognize here. See above.
   repeated UninterpretedOption uninterpreted_option = 999;
@@ -668,9 +719,11 @@ message FieldOptions {
   extensions 1000 to max;
 
   reserved 4;  // removed jtype
+  optional OptionTargetType target_obsolete_do_not_use = 18 [deprecated = true];
 }
 
 message OneofOptions {
+
   // The parser stores options it doesn't recognize here. See above.
   repeated UninterpretedOption uninterpreted_option = 999;
 
diff --git a/dev/protos/google/protobuf/timestamp.proto b/dev/protos/google/protobuf/timestamp.proto
index 2fb527c0c..fd0bc07dc 100644
--- a/dev/protos/google/protobuf/timestamp.proto
+++ b/dev/protos/google/protobuf/timestamp.proto
@@ -127,7 +127,7 @@ option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 // [`strftime`](https://docs.python.org/2/library/time.html#time.strftime) with
 // the time format spec '%Y-%m-%dT%H:%M:%S.%fZ'. Likewise, in Java, one can use
 // the Joda Time's [`ISODateTimeFormat.dateTime()`](
-// http://www.joda.org/joda-time/apidocs/org/joda/time/format/ISODateTimeFormat.html#dateTime%2D%2D
+// http://joda-time.sourceforge.net/apidocs/org/joda/time/format/ISODateTimeFormat.html#dateTime()
 // ) to obtain a formatter capable of generating timestamps in this format.
 //
 message Timestamp {
diff --git a/dev/src/filter.ts b/dev/src/filter.ts
index d12eaa8cc..7b50b1efb 100644
--- a/dev/src/filter.ts
+++ b/dev/src/filter.ts
@@ -94,7 +94,7 @@ export abstract class Filter {
   /**
    * Creates and returns a new [Filter]{@link Filter} that is a
    * conjunction of the given {@link Filter}s. A conjunction filter includes
-   * a document if it satisfies any of the given {@link Filter}s.
+   * a document if it satisfies all of the given {@link Filter}s.
    *
    * The returned Filter can be applied to [Query.where()]{@link Query#where},
    * [Filter.or()]{@link Filter#or}, or [Filter.and()]{@link Filter#and}. When
diff --git a/dev/src/index.ts b/dev/src/index.ts
index 74a81f300..9abb4964d 100644
--- a/dev/src/index.ts
+++ b/dev/src/index.ts
@@ -60,6 +60,7 @@ import {
   isPermanentRpcError,
   requestTag,
   wrapError,
+  tryGetPreferRestEnvironmentVariable,
 } from './util';
 import {
   validateBoolean,
@@ -534,7 +535,12 @@ export class Firestore implements firestore.Firestore {
    * for communication from that point forward. Currently the only operation
    * that requires gRPC is creating a snapshot listener with the method
    * `DocumentReference<T>.onSnapshot()`, `CollectionReference<T>.onSnapshot()`, or
-   * `Query<T>.onSnapshot()`.
+   * `Query<T>.onSnapshot()`. If specified, this setting value will take precedent over the
+   * environment variable `FIRESTORE_PREFER_REST`. If not specified, the
+   * SDK will use the value specified in the environment variable `FIRESTORE_PREFER_REST`.
+   * Valid values of `FIRESTORE_PREFER_REST` are `true` ('1') or `false` (`0`). Values are
+   * not case-sensitive. Any other value for the environment variable will be ignored and
+   * a warning will be logged to the console.
    */
   constructor(settings?: firestore.Settings) {
     const libraryHeader = {
@@ -663,6 +669,16 @@ export class Firestore implements firestore.Firestore {
 
     let url: URL | null = null;
 
+    // If preferRest is not specified in settings, but is set as environment variable,
+    // then use the environment variable value.
+    const preferRestEnvValue = tryGetPreferRestEnvironmentVariable();
+    if (settings.preferRest === undefined && preferRestEnvValue !== undefined) {
+      settings = {
+        ...settings,
+        preferRest: preferRestEnvValue,
+      };
+    }
+
     // If the environment variable is set, it should always take precedence
     // over any user passed in settings.
     if (process.env.FIRESTORE_EMULATOR_HOST) {
diff --git a/dev/src/util.ts b/dev/src/util.ts
index 5a189269c..cf91f4ee0 100644
--- a/dev/src/util.ts
+++ b/dev/src/util.ts
@@ -217,3 +217,32 @@ export function wrapError(err: Error, stack: string): Error {
   err.stack += '\nCaused by: ' + stack;
   return err;
 }
+
+/**
+ * Parses the value of the environment variable FIRESTORE_PREFER_REST, and
+ * returns a value indicating if the environment variable enables or disables
+ * preferRest.
+ *
+ * This function will warn to the console if the environment variable is set
+ * to an unsupported value.
+ *
+ * @return `true` if the environment variable enables `preferRest`,
+ * `false` if the environment variable disables `preferRest`, or `undefined`
+ * if the environment variable is not set or is set to an unsupported value.
+ */
+export function tryGetPreferRestEnvironmentVariable(): boolean | undefined {
+  const rawValue = process.env.FIRESTORE_PREFER_REST?.trim().toLowerCase();
+  if (rawValue === undefined) {
+    return undefined;
+  } else if (rawValue === '1' || rawValue === 'true') {
+    return true;
+  } else if (rawValue === '0' || rawValue === 'false') {
+    return false;
+  } else {
+    // eslint-disable-next-line no-console
+    console.warn(
+      `An unsupported value was specified for the environment variable FIRESTORE_PREFER_REST. Value ${rawValue} is unsupported.`
+    );
+    return undefined;
+  }
+}
diff --git a/dev/src/v1/firestore_client.ts b/dev/src/v1/firestore_client.ts
index 000c07cf4..48cf4f453 100644
--- a/dev/src/v1/firestore_client.ts
+++ b/dev/src/v1/firestore_client.ts
@@ -1326,7 +1326,7 @@ export class FirestoreClient {
 
   /**
    * Streams batches of document updates and deletes, in order. This method is
-   * only available via the gRPC API (not REST).
+   * only available via gRPC or WebChannel (not REST).
    *
    * @param {object} [options]
    *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
@@ -1346,8 +1346,8 @@ export class FirestoreClient {
   }
 
   /**
-   * Listens to changes. This method is only available via the gRPC API (not
-   * REST).
+   * Listens to changes. This method is only available via gRPC or WebChannel
+   * (not REST).
    *
    * @param {object} [options]
    *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
diff --git a/dev/src/v1/firestore_proto_list.json b/dev/src/v1/firestore_proto_list.json
index ebe9cbb60..5c2cd76e2 100644
--- a/dev/src/v1/firestore_proto_list.json
+++ b/dev/src/v1/firestore_proto_list.json
@@ -1,5 +1,6 @@
 [
   "../../protos/google/firestore/v1/aggregation_result.proto",
+  "../../protos/google/firestore/v1/bloom_filter.proto",
   "../../protos/google/firestore/v1/common.proto",
   "../../protos/google/firestore/v1/document.proto",
   "../../protos/google/firestore/v1/firestore.proto",
diff --git a/dev/system-test/firestore.ts b/dev/system-test/firestore.ts
index d87114381..964b832e4 100644
--- a/dev/system-test/firestore.ts
+++ b/dev/system-test/firestore.ts
@@ -84,7 +84,6 @@ if (process.env.NODE_ENV === 'DEBUG') {
 function getTestRoot(settings: Settings = {}) {
   const firestore = new Firestore({
     ...settings,
-    preferRest: !!process.env.USE_REST_FALLBACK,
   });
   return firestore.collection(`node_${version}_${autoId()}`);
 }
diff --git a/dev/test/index.ts b/dev/test/index.ts
index 4fa7d6e93..12df809ec 100644
--- a/dev/test/index.ts
+++ b/dev/test/index.ts
@@ -639,6 +639,62 @@ describe('instantiation', () => {
     );
   });
 
+  describe('preferRest configuration', () => {
+    let originalValue: string | undefined;
+
+    beforeEach(() => {
+      originalValue = process.env.FIRESTORE_PREFER_REST;
+    });
+
+    afterEach(() => {
+      if (originalValue === undefined) {
+        delete process.env.FIRESTORE_PREFER_REST;
+      } else {
+        process.env.FIRESTORE_PREFER_REST = originalValue;
+      }
+    });
+
+    it('preferRest is disabled (falsy) by default', async () => {
+      delete process.env.FIRESTORE_PREFER_REST;
+      const firestore = new Firestore.Firestore({});
+      // Convention with settings is to leave undefined settings as
+      // undefined. We could test for undefined here, but converting
+      // to boolean and testing for falsy-ness is consistent with the
+      // code that consumes settings.
+      expect(!!firestore['_settings'].preferRest).to.be.false;
+    });
+
+    it('preferRest can be enabled by setting', async () => {
+      delete process.env.FIRESTORE_PREFER_REST;
+      const firestore = new Firestore.Firestore({
+        preferRest: true,
+      });
+      expect(firestore['_settings'].preferRest).to.be.true;
+    });
+
+    it('preferRest can be enabled by environment variable', async () => {
+      process.env.FIRESTORE_PREFER_REST = 'true';
+      const firestore = new Firestore.Firestore({});
+      expect(firestore['_settings'].preferRest).to.be.true;
+    });
+
+    it('the preferRest value from settings takes precedent over the environment var - disable', async () => {
+      process.env.FIRESTORE_PREFER_REST = 'true';
+      const firestore = new Firestore.Firestore({
+        preferRest: false,
+      });
+      expect(firestore['_settings'].preferRest).to.be.false;
+    });
+
+    it('the preferRest value from settings takes precedent over the environment var - enable', async () => {
+      process.env.FIRESTORE_PREFER_REST = 'false';
+      const firestore = new Firestore.Firestore({
+        preferRest: true,
+      });
+      expect(firestore['_settings'].preferRest).to.be.true;
+    });
+  });
+
   it('exports all types', () => {
     // Ordering as per firestore.d.ts
     expect(Firestore.Firestore).to.exist;
diff --git a/dev/test/util.ts b/dev/test/util.ts
index c4687eef7..7806f74d2 100644
--- a/dev/test/util.ts
+++ b/dev/test/util.ts
@@ -14,7 +14,8 @@
 
 import {describe, it} from 'mocha';
 import {expect} from 'chai';
-import {isPlainObject} from '../src/util';
+import {isPlainObject, tryGetPreferRestEnvironmentVariable} from '../src/util';
+import * as sinon from 'sinon';
 
 describe('isPlainObject()', () => {
   it('allows Object.create()', () => {
@@ -33,4 +34,71 @@ describe('isPlainObject()', () => {
     expect(isPlainObject(new Foo())).to.be.false;
     expect(isPlainObject(Object.create(new Foo()))).to.be.false;
   });
+
+  describe('tryGetPreferRestEnvironmentVariable', () => {
+    const sandbox = sinon.createSandbox();
+
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    let warnSpy: any;
+    let originalValue: string | undefined;
+
+    beforeEach(() => {
+      warnSpy = sandbox.spy(console, 'warn');
+      originalValue = process.env.FIRESTORE_PREFER_REST;
+    });
+
+    afterEach(() => {
+      sandbox.restore();
+      if (originalValue === undefined) {
+        delete process.env.FIRESTORE_PREFER_REST;
+      } else {
+        process.env.FIRESTORE_PREFER_REST = originalValue;
+      }
+    });
+
+    it('reads true', async () => {
+      process.env.FIRESTORE_PREFER_REST = 'true';
+      expect(tryGetPreferRestEnvironmentVariable()).to.be.true;
+    });
+
+    it('reads 1', async () => {
+      process.env.FIRESTORE_PREFER_REST = '1';
+      expect(tryGetPreferRestEnvironmentVariable()).to.be.true;
+    });
+
+    it('reads false', async () => {
+      process.env.FIRESTORE_PREFER_REST = 'false';
+      expect(tryGetPreferRestEnvironmentVariable()).to.be.false;
+    });
+
+    it('reads 0', async () => {
+      process.env.FIRESTORE_PREFER_REST = '0';
+      expect(tryGetPreferRestEnvironmentVariable()).to.be.false;
+    });
+
+    it('ignores case', async () => {
+      process.env.FIRESTORE_PREFER_REST = 'True';
+      expect(tryGetPreferRestEnvironmentVariable()).to.be.true;
+    });
+
+    it('trims whitespace', async () => {
+      process.env.FIRESTORE_PREFER_REST = '  true  ';
+      expect(tryGetPreferRestEnvironmentVariable()).to.be.true;
+    });
+
+    it('returns undefined when the environment variable is not set', async () => {
+      delete process.env.FIRESTORE_PREFER_REST;
+      expect(tryGetPreferRestEnvironmentVariable()).to.be.undefined;
+      expect(warnSpy.calledOnce).to.be.false;
+    });
+
+    it('returns undefined and warns when the environment variable is set to an unsupported value', async () => {
+      process.env.FIRESTORE_PREFER_REST = 'enable';
+      expect(tryGetPreferRestEnvironmentVariable()).to.be.undefined;
+      expect(warnSpy.calledOnce).to.be.true;
+      expect(warnSpy.getCall(0).args[0]).to.match(
+        /unsupported value.*FIRESTORE_PREFER_REST/
+      );
+    });
+  });
 });
diff --git a/dev/test/util/helpers.ts b/dev/test/util/helpers.ts
index 476804b37..ea9b1802f 100644
--- a/dev/test/util/helpers.ts
+++ b/dev/test/util/helpers.ts
@@ -35,7 +35,7 @@ import {GapicClient} from '../../src/types';
 import api = proto.google.firestore.v1;
 
 let SSL_CREDENTIALS: grpc.ChannelCredentials | null = null;
-if (!process.env.USE_REST_FALLBACK) {
+if (!isPreferRest()) {
   const grpc = require('google-gax').grpc;
   SSL_CREDENTIALS = grpc.credentials.createInsecure();
 }
@@ -444,3 +444,16 @@ export async function collect<T, TReturn, TNext>(
   }
   return values;
 }
+
+/**
+ * Returns a value indicating whether preferRest is enabled
+ * via the environment variable `FIRESTORE_PREFER_REST`.
+ *
+ * @return `true` if preferRest is enabled via the environment variable `FIRESTORE_PREFER_REST`.
+ */
+export function isPreferRest(): boolean {
+  return (
+    process.env.FIRESTORE_PREFER_REST === '1' ||
+    process.env.FIRESTORE_PREFER_REST === 'true'
+  );
+}
diff --git a/package.json b/package.json
index b17b62c14..37d003e5f 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "@google-cloud/firestore",
   "description": "Firestore Client Library for Node.js",
-  "version": "6.5.0",
+  "version": "6.6.0",
   "license": "Apache-2.0",
   "author": "Google Inc.",
   "engines": {
@@ -30,9 +30,9 @@
   "scripts": {
     "predocs": "npm run compile",
     "docs": "jsdoc -c .jsdoc.js",
-    "system-test:rest": "USE_REST_FALLBACK=YES mocha build/system-test --timeout 600000",
+    "system-test:rest": "FIRESTORE_PREFER_REST=true mocha build/system-test --timeout 600000",
     "system-test:grpc": "mocha build/system-test --timeout 600000",
-    "system-test:emulator:rest": "FIRESTORE_EMULATOR_HOST=localhost:8080 USE_REST_FALLBACK=YES mocha build/system-test --timeout 600000",
+    "system-test:emulator:rest": "FIRESTORE_EMULATOR_HOST=localhost:8080 FIRESTORE_PREFER_REST=true mocha build/system-test --timeout 600000",
     "system-test:emulator:grpc": "FIRESTORE_EMULATOR_HOST=localhost:8080 mocha build/system-test --timeout 600000",
     "system-test": "npm run system-test:grpc && npm run system-test:rest",
     "system-test:emulator": "npm run system-test:emulator:grpc && npm run system-test:emulator:rest",
diff --git a/samples/package.json b/samples/package.json
index af501f537..1cd21edeb 100644
--- a/samples/package.json
+++ b/samples/package.json
@@ -11,7 +11,7 @@
     "test": "mocha --timeout 600000"
   },
   "dependencies": {
-    "@google-cloud/firestore": "^6.5.0"
+    "@google-cloud/firestore": "^6.6.0"
   },
   "devDependencies": {
     "chai": "^4.2.0",
diff --git a/types/firestore.d.ts b/types/firestore.d.ts
index 964538197..5c5459c44 100644
--- a/types/firestore.d.ts
+++ b/types/firestore.d.ts
@@ -2513,7 +2513,7 @@ declare namespace FirebaseFirestore {
     /**
      * Creates and returns a new [Filter]{@link Filter} that is a
      * conjunction of the given {@link Filter}s. A conjunction filter includes
-     * a document if it satisfies any of the given {@link Filter}s.
+     * a document if it satisfies all of the given {@link Filter}s.
      *
      * The returned Filter can be applied to [Query.where()]{@link Query#where},
      * [Filter.or()]{@link Filter#or}, or [Filter.and()]{@link Filter#and}. When