diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 6b7b74c..da59f99 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "0.3.0"
+  ".": "0.4.0"
 }
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 862bb8e..79c2f09 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,29 @@
 # Changelog
 
+## [0.4.0](https://github.com/googleapis/java-vertexai/compare/v0.3.0...v0.4.0) (2026-09-01)
+
+
+### Features
+
+* Add a top-level `client.sandboxes` accessor to the Vertex AI GenAI SDK for Java, with `environments`, `templates`, and `snapshots` submodules. ([7dc24fb](https://github.com/googleapis/java-vertexai/commit/7dc24fbdb334012f2c04048dbf8211fcca1a25e4))
+* Add enable_data_retention to ToolParallelAiSearch, Add step_count to ReinforcementTuningHyperParameters, Add BidiGenerateContentSetup ([3bb6b4c](https://github.com/googleapis/java-vertexai/commit/3bb6b4cbd810f77dde164b367ec69862d8dab1fa))
+* Add sandbox templates and snapshots submodules to the Vertex AI GenAI SDK for Java. ([73bd43f](https://github.com/googleapis/java-vertexai/commit/73bd43f4e03449dd7bd977a87f136804d55fab5c))
+* Add sandboxes.pause() and sandboxes.resume() methods to the Agent Engine sandbox SDK across Python, Java, and JS SDKs. ([d8ad68e](https://github.com/googleapis/java-vertexai/commit/d8ad68e826de3b3317d5dff1af3f7095abeba43d))
+* Add Shell Sandbox environment support to the Agent Engine sandbox SDK ([8639493](https://github.com/googleapis/java-vertexai/commit/863949378fb3b4679ee01d022c13a83b4182fa25))
+* **agentplatform:** Support client.memory_banks.get ([c6af60d](https://github.com/googleapis/java-vertexai/commit/c6af60de76088dad9cccad74ac35d0ff44910c91))
+* **agentplatform:** Support client.memory_banks.list ([c6af60d](https://github.com/googleapis/java-vertexai/commit/c6af60de76088dad9cccad74ac35d0ff44910c91))
+* **agentplatform:** Support Memory Bank configs. ([c6af60d](https://github.com/googleapis/java-vertexai/commit/c6af60de76088dad9cccad74ac35d0ff44910c91))
+* Allow setting `ingress_control_config` when creating a `SandboxEnvironmentTemplate` via the SDK (Python, Java, JS). ([1e95097](https://github.com/googleapis/java-vertexai/commit/1e950974b3865f9bdc828afc300ec836213601f8))
+* Expose ingress_control_config field on SandboxEnvironmentTemplate across Python, Java, and JS SDKs. ([4507f78](https://github.com/googleapis/java-vertexai/commit/4507f78c58bcdf6b11bf70fec75db228cc96f19d))
+* Expose SandboxEnvironmentTemplateState as a standalone enum class in the Python, Java, and JS SDKs. ([2eb6999](https://github.com/googleapis/java-vertexai/commit/2eb6999f739b133025984b77e707b2e2ca4b6d6b))
+* Expose service_attachment field on SandboxEnvironmentConnectionInfo across Python, Java, JS, and Go SDKs. ([adb993b](https://github.com/googleapis/java-vertexai/commit/adb993b79f794af4454b99e649304107d4f8da14))
+* Expose STATE_PAUSED, STATE_PAUSING, and STATE_RESUMING values in the SandboxState enum for SandboxEnvironment across Python, Java, and JS SDKs. ([b5d9819](https://github.com/googleapis/java-vertexai/commit/b5d9819f91c568058a6335d48be1e41505266ee6))
+
+
+### Bug Fixes
+
+* Update generator configuration and SDK bindings for Agent Engine Session update calls to return Session directly. ([037692b](https://github.com/googleapis/java-vertexai/commit/037692bb6807c73f7df3abdfe295db45f31c298a))
+
 ## [0.3.0](https://github.com/googleapis/java-vertexai/compare/v0.2.0...v0.3.0) (2026-07-06)
 
 
diff --git a/README.md b/README.md
index e02b073..6eaa161 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-agentplatform</artifactId>
-  <version>0.3.0</version>
+  <version>0.4.0</version>
 </dependency>
 ```
 <!-- {x-version-update-end} -->
diff --git a/examples/pom.xml b/examples/pom.xml
index 9ccec6c..09b8e1e 100644
--- a/examples/pom.xml
+++ b/examples/pom.xml
@@ -5,7 +5,7 @@
 
   <groupId>com.google.cloud.agentplatform.examples</groupId>
   <artifactId>google-agentplatform-examples</artifactId>
-  <version>0.4.0-SNAPSHOT</version><!-- {x-version-update:google-cloud-agentplatform:current} -->
+  <version>0.4.0</version><!-- {x-version-update:google-cloud-agentplatform:current} -->
   <name>google-agentplatform-examples</name>
 
   <properties>
@@ -13,7 +13,7 @@
     <maven.compiler.source>1.8</maven.compiler.source>
     <maven.compiler.target>1.8</maven.compiler.target>
     <!-- {x-version-update-start:google-cloud-agentplatform:current} -->
-    <google-cloud-agentplatform.version>0.4.0-SNAPSHOT</google-cloud-agentplatform.version>
+    <google-cloud-agentplatform.version>0.4.0</google-cloud-agentplatform.version>
     <!-- {x-version-update-end} -->
   </properties>
   <build>
diff --git a/pom.xml b/pom.xml
index 97ee7ee..7a8e483 100644
--- a/pom.xml
+++ b/pom.xml
@@ -3,7 +3,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-agentplatform</artifactId>
-  <version>0.4.0-SNAPSHOT</version><!-- {x-version-update:google-cloud-agentplatform:current} -->
+  <version>0.4.0</version><!-- {x-version-update:google-cloud-agentplatform:current} -->
   <packaging>jar</packaging>
   <name>google-cloud-agentplatform</name>
   <description>
diff --git a/src/main/java/com/google/cloud/agentplatform/Client.java b/src/main/java/com/google/cloud/agentplatform/Client.java
index 7b62285..332ddf1 100644
--- a/src/main/java/com/google/cloud/agentplatform/Client.java
+++ b/src/main/java/com/google/cloud/agentplatform/Client.java
@@ -54,7 +54,7 @@ public Async(ApiClient apiClient) {
   }
 
   // {x-version-update-start:google-cloud-agentplatform:released}
-  private static final String SDK_VERSION = "0.3.0";
+  private static final String SDK_VERSION = "0.4.0";
   // {x-version-update-end:google-cloud-agentplatform:released}
   private static final ImmutableMap<String, String> TRACKING_HEADERS;
   private static final Logger logger = Logger.getLogger(Client.class.getName());
diff --git a/versions.txt b/versions.txt
index 6a3cf04..7fc6d8e 100644
--- a/versions.txt
+++ b/versions.txt
@@ -1,4 +1,4 @@
 # Format:
 # module:released-version:current-version
 
-google-cloud-agentplatform:0.3.0:0.4.0-SNAPSHOT
\ No newline at end of file
+google-cloud-agentplatform:0.4.0:0.4.0
\ No newline at end of file