diff --git a/CHANGELOG.md b/CHANGELOG.md
index 348c2a9db34..a7dc0a4b214 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,29 @@
 # Changelog
 
+## [6.6.0](https://www.github.com/googleapis/java-spanner/compare/v6.5.0...v6.6.0) (2021-06-07)
+
+
+### Features
+
+* adds query optimizer statistics support ([#385](https://www.github.com/googleapis/java-spanner/issues/385)) ([e294532](https://www.github.com/googleapis/java-spanner/commit/e2945324783bc6d5a7a323578e8dbf00969f3163))
+* support encoded credentials in connection URL ([#1223](https://www.github.com/googleapis/java-spanner/issues/1223)) ([43d5d7e](https://www.github.com/googleapis/java-spanner/commit/43d5d7e8d7fc1b0304a6fcf940846fe269fd661a))
+
+
+### Documentation
+
+* document retry settings in sample ([#1214](https://www.github.com/googleapis/java-spanner/issues/1214)) ([ab4592d](https://www.github.com/googleapis/java-spanner/commit/ab4592d6f5040d0125b2848369c516d01fd38106))
+
+
+### Dependencies
+
+* update dependency com.google.cloud:google-cloud-monitoring to v2.3.0 ([#1225](https://www.github.com/googleapis/java-spanner/issues/1225)) ([2023839](https://www.github.com/googleapis/java-spanner/commit/2023839cce80de0ff6451a4b6274f5da9b18416f))
+* update dependency com.google.cloud:google-cloud-monitoring to v2.3.2 ([#1229](https://www.github.com/googleapis/java-spanner/issues/1229)) ([8a23ad0](https://www.github.com/googleapis/java-spanner/commit/8a23ad047ec7fc4a8a5c8d6292678e579c323eb2))
+* update dependency com.google.cloud:google-cloud-shared-dependencies to v1.3.0 ([#1230](https://www.github.com/googleapis/java-spanner/issues/1230)) ([db64451](https://www.github.com/googleapis/java-spanner/commit/db6445133de143391dbd9da6d3393b0d2736971a))
+* update dependency com.google.cloud:google-cloud-trace to v1.4.0 ([#1226](https://www.github.com/googleapis/java-spanner/issues/1226)) ([da4407a](https://www.github.com/googleapis/java-spanner/commit/da4407a60fb2917d1ea8043b57bdff41263af241))
+* update dependency com.google.cloud:google-cloud-trace to v1.4.1 ([#1231](https://www.github.com/googleapis/java-spanner/issues/1231)) ([76af3ac](https://www.github.com/googleapis/java-spanner/commit/76af3ace6d6745673006cc1a529d66a74513c615))
+* update dependency org.openjdk.jmh:jmh-core to v1.32 ([#1221](https://www.github.com/googleapis/java-spanner/issues/1221)) ([b009c9b](https://www.github.com/googleapis/java-spanner/commit/b009c9b09a9200a674b629cc74a479f8b746e727))
+* update dependency org.openjdk.jmh:jmh-generator-annprocess to v1.32 ([#1222](https://www.github.com/googleapis/java-spanner/issues/1222)) ([7ef76a9](https://www.github.com/googleapis/java-spanner/commit/7ef76a910defd6f9cd24191de4eb0c523a294fea))
+
 ## [6.5.0](https://www.github.com/googleapis/java-spanner/compare/v6.4.4...v6.5.0) (2021-05-25)
 
 
diff --git a/google-cloud-spanner-bom/pom.xml b/google-cloud-spanner-bom/pom.xml
index 115c55160f9..82cd3cbbc3a 100644
--- a/google-cloud-spanner-bom/pom.xml
+++ b/google-cloud-spanner-bom/pom.xml
@@ -3,7 +3,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-spanner-bom</artifactId>
-  <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+  <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
   <packaging>pom</packaging>
   <parent>
     <groupId>com.google.cloud</groupId>
@@ -64,43 +64,43 @@
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-google-cloud-spanner-admin-instance-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:proto-google-cloud-spanner-admin-instance-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:proto-google-cloud-spanner-admin-instance-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>grpc-google-cloud-spanner-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:grpc-google-cloud-spanner-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:grpc-google-cloud-spanner-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-google-cloud-spanner-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:proto-google-cloud-spanner-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:proto-google-cloud-spanner-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-google-cloud-spanner-admin-database-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:proto-google-cloud-spanner-admin-database-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:proto-google-cloud-spanner-admin-database-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-spanner</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+        <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-spanner</artifactId>
         <type>test-jar</type>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+        <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>grpc-google-cloud-spanner-admin-instance-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-instance-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-instance-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>grpc-google-cloud-spanner-admin-database-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-database-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-database-v1:current} -->
       </dependency>
     </dependencies>
   </dependencyManagement>
diff --git a/google-cloud-spanner/pom.xml b/google-cloud-spanner/pom.xml
index 6755f36a5c8..86c8149e51f 100644
--- a/google-cloud-spanner/pom.xml
+++ b/google-cloud-spanner/pom.xml
@@ -3,7 +3,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-spanner</artifactId>
-  <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+  <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
   <packaging>jar</packaging>
   <name>Google Cloud Spanner</name>
   <url>https://github.com/googleapis/java-spanner</url>
@@ -11,7 +11,7 @@
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-spanner-parent</artifactId>
-    <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+    <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
   </parent>
   <properties>
     <site.installationModule>google-cloud-spanner</site.installationModule>
diff --git a/grpc-google-cloud-spanner-admin-database-v1/pom.xml b/grpc-google-cloud-spanner-admin-database-v1/pom.xml
index fe77dc2f1ae..d056c54ebb7 100644
--- a/grpc-google-cloud-spanner-admin-database-v1/pom.xml
+++ b/grpc-google-cloud-spanner-admin-database-v1/pom.xml
@@ -4,13 +4,13 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.api.grpc</groupId>
   <artifactId>grpc-google-cloud-spanner-admin-database-v1</artifactId>
-  <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-database-v1:current} -->
+  <version>6.6.0</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-database-v1:current} -->
   <name>grpc-google-cloud-spanner-admin-database-v1</name>
   <description>GRPC library for grpc-google-cloud-spanner-admin-database-v1</description>
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-spanner-parent</artifactId>
-    <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+    <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
   </parent>
   <dependencies>
     <dependency>
diff --git a/grpc-google-cloud-spanner-admin-instance-v1/pom.xml b/grpc-google-cloud-spanner-admin-instance-v1/pom.xml
index f1bdc1fb2d8..2643280a066 100644
--- a/grpc-google-cloud-spanner-admin-instance-v1/pom.xml
+++ b/grpc-google-cloud-spanner-admin-instance-v1/pom.xml
@@ -4,13 +4,13 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.api.grpc</groupId>
   <artifactId>grpc-google-cloud-spanner-admin-instance-v1</artifactId>
-  <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-instance-v1:current} -->
+  <version>6.6.0</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-instance-v1:current} -->
   <name>grpc-google-cloud-spanner-admin-instance-v1</name>
   <description>GRPC library for grpc-google-cloud-spanner-admin-instance-v1</description>
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-spanner-parent</artifactId>
-    <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+    <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
   </parent>
   <dependencies>
     <dependency>
diff --git a/grpc-google-cloud-spanner-v1/pom.xml b/grpc-google-cloud-spanner-v1/pom.xml
index ea8ef545025..135f30284ad 100644
--- a/grpc-google-cloud-spanner-v1/pom.xml
+++ b/grpc-google-cloud-spanner-v1/pom.xml
@@ -4,13 +4,13 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.api.grpc</groupId>
   <artifactId>grpc-google-cloud-spanner-v1</artifactId>
-  <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:grpc-google-cloud-spanner-v1:current} -->
+  <version>6.6.0</version><!-- {x-version-update:grpc-google-cloud-spanner-v1:current} -->
   <name>grpc-google-cloud-spanner-v1</name>
   <description>GRPC library for grpc-google-cloud-spanner-v1</description>
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-spanner-parent</artifactId>
-    <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+    <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
   </parent>
   <dependencies>
     <dependency>
diff --git a/pom.xml b/pom.xml
index fd77d961031..6b8ac555418 100644
--- a/pom.xml
+++ b/pom.xml
@@ -4,7 +4,7 @@
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-spanner-parent</artifactId>
   <packaging>pom</packaging>
-  <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+  <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
   <name>Google Cloud Spanner Parent</name>
   <url>https://github.com/googleapis/java-spanner</url>
   <description>
@@ -71,37 +71,37 @@
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-google-cloud-spanner-admin-instance-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:proto-google-cloud-spanner-admin-instance-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:proto-google-cloud-spanner-admin-instance-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-google-cloud-spanner-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:proto-google-cloud-spanner-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:proto-google-cloud-spanner-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-google-cloud-spanner-admin-database-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:proto-google-cloud-spanner-admin-database-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:proto-google-cloud-spanner-admin-database-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>grpc-google-cloud-spanner-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:grpc-google-cloud-spanner-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:grpc-google-cloud-spanner-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>grpc-google-cloud-spanner-admin-instance-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-instance-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-instance-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>grpc-google-cloud-spanner-admin-database-v1</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-database-v1:current} -->
+        <version>6.6.0</version><!-- {x-version-update:grpc-google-cloud-spanner-admin-database-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-spanner</artifactId>
-        <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+        <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
       </dependency>
 
       <dependency>
diff --git a/proto-google-cloud-spanner-admin-database-v1/pom.xml b/proto-google-cloud-spanner-admin-database-v1/pom.xml
index a7f21a66c94..915101d3ab6 100644
--- a/proto-google-cloud-spanner-admin-database-v1/pom.xml
+++ b/proto-google-cloud-spanner-admin-database-v1/pom.xml
@@ -4,13 +4,13 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.api.grpc</groupId>
   <artifactId>proto-google-cloud-spanner-admin-database-v1</artifactId>
-  <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:proto-google-cloud-spanner-admin-database-v1:current} -->
+  <version>6.6.0</version><!-- {x-version-update:proto-google-cloud-spanner-admin-database-v1:current} -->
   <name>proto-google-cloud-spanner-admin-database-v1</name>
   <description>PROTO library for proto-google-cloud-spanner-admin-database-v1</description>
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-spanner-parent</artifactId>
-    <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+    <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
   </parent>
   <dependencies>
     <dependency>
diff --git a/proto-google-cloud-spanner-admin-instance-v1/pom.xml b/proto-google-cloud-spanner-admin-instance-v1/pom.xml
index a16fcb730a1..3c31afa7d67 100644
--- a/proto-google-cloud-spanner-admin-instance-v1/pom.xml
+++ b/proto-google-cloud-spanner-admin-instance-v1/pom.xml
@@ -4,13 +4,13 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.api.grpc</groupId>
   <artifactId>proto-google-cloud-spanner-admin-instance-v1</artifactId>
-  <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:proto-google-cloud-spanner-admin-instance-v1:current} -->
+  <version>6.6.0</version><!-- {x-version-update:proto-google-cloud-spanner-admin-instance-v1:current} -->
   <name>proto-google-cloud-spanner-admin-instance-v1</name>
   <description>PROTO library for proto-google-cloud-spanner-admin-instance-v1</description>
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-spanner-parent</artifactId>
-    <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+    <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
   </parent>
   <dependencies>
     <dependency>
diff --git a/proto-google-cloud-spanner-v1/pom.xml b/proto-google-cloud-spanner-v1/pom.xml
index 4842792c294..8e8098943dc 100644
--- a/proto-google-cloud-spanner-v1/pom.xml
+++ b/proto-google-cloud-spanner-v1/pom.xml
@@ -4,13 +4,13 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.api.grpc</groupId>
   <artifactId>proto-google-cloud-spanner-v1</artifactId>
-  <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:proto-google-cloud-spanner-v1:current} -->
+  <version>6.6.0</version><!-- {x-version-update:proto-google-cloud-spanner-v1:current} -->
   <name>proto-google-cloud-spanner-v1</name>
   <description>PROTO library for proto-google-cloud-spanner-v1</description>
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-spanner-parent</artifactId>
-    <version>6.5.1-SNAPSHOT</version><!-- {x-version-update:google-cloud-spanner:current} -->
+    <version>6.6.0</version><!-- {x-version-update:google-cloud-spanner:current} -->
   </parent>
   <dependencies>
     <dependency>
diff --git a/samples/snapshot/pom.xml b/samples/snapshot/pom.xml
index 44ada332295..0314dc92d55 100644
--- a/samples/snapshot/pom.xml
+++ b/samples/snapshot/pom.xml
@@ -31,7 +31,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-spanner</artifactId>
-      <version>6.5.1-SNAPSHOT</version>
+      <version>6.6.0</version>
     </dependency>
     <!-- {x-version-update-end} -->
     
diff --git a/versions.txt b/versions.txt
index 98fe37245a5..47919909486 100644
--- a/versions.txt
+++ b/versions.txt
@@ -1,10 +1,10 @@
 # Format:
 # module:released-version:current-version
 
-proto-google-cloud-spanner-admin-instance-v1:6.5.0:6.5.1-SNAPSHOT
-proto-google-cloud-spanner-v1:6.5.0:6.5.1-SNAPSHOT
-proto-google-cloud-spanner-admin-database-v1:6.5.0:6.5.1-SNAPSHOT
-grpc-google-cloud-spanner-v1:6.5.0:6.5.1-SNAPSHOT
-grpc-google-cloud-spanner-admin-instance-v1:6.5.0:6.5.1-SNAPSHOT
-grpc-google-cloud-spanner-admin-database-v1:6.5.0:6.5.1-SNAPSHOT
-google-cloud-spanner:6.5.0:6.5.1-SNAPSHOT
\ No newline at end of file
+proto-google-cloud-spanner-admin-instance-v1:6.6.0:6.6.0
+proto-google-cloud-spanner-v1:6.6.0:6.6.0
+proto-google-cloud-spanner-admin-database-v1:6.6.0:6.6.0
+grpc-google-cloud-spanner-v1:6.6.0:6.6.0
+grpc-google-cloud-spanner-admin-instance-v1:6.6.0:6.6.0
+grpc-google-cloud-spanner-admin-database-v1:6.6.0:6.6.0
+google-cloud-spanner:6.6.0:6.6.0
\ No newline at end of file