diff --git a/CHANGELOG.md b/CHANGELOG.md
index 72e0c7b1..93dc505a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,46 @@
 # Changelog
 
+## [1.20.0](https://github.com/google/adk-python/compare/v1.19.0...v1.20.0) (2025-12-01)
+
+
+### Features
+* **[Core]**
+  * Add enum constraint to `agent_name` for `transfer_to_agent` ([4a42d0d](https://github.com/google/adk-python/commit/4a42d0d9d81b7aab98371427f70a7707dbfb8bc4))
+  * Add validation for unique sub-agent names ([#3557](https://github.com/google/adk-python/issues/3557)) ([2247a45](https://github.com/google/adk-python/commit/2247a45922afdf0a733239b619f45601d9b325ec))
+  * Support streaming function call arguments in progressive SSE streaming feature ([786aaed](https://github.com/google/adk-python/commit/786aaed335e1ce64b7e92dff2f4af8316b2ef593))
+
+* **[Models]**
+  * Enable multi-provider support for Claude and LiteLLM ([d29261a](https://github.com/google/adk-python/commit/d29261a3dc9c5a603feef27ea657c4a03bb8a089))
+
+* **[Tools]**
+  * Create APIRegistryToolset to add tools from Cloud API registry to agent ([ec4ccd7](https://github.com/google/adk-python/commit/ec4ccd718feeadeb6b2b59fcc0e9ff29a4fd0bac))
+  * Add an option to disallow propagating runner plugins to AgentTool runner ([777dba3](https://github.com/google/adk-python/commit/777dba3033a9a14667fb009ba017f648177be41d))
+
+* **[Web]**
+  * Added an endpoint to list apps with details ([b57fe5f](https://github.com/google/adk-python/commit/b57fe5f4598925ec7592917bb32c7f0d6eca287a))
+
+
+### Bug Fixes
+
+* Allow image parts in user messages for Anthropic Claude ([5453b5b](https://github.com/google/adk-python/commit/5453b5bfdedc91d9d668c9eac39e3bb009a7bbbf))
+* Mark the Content as non-empty if its first part contains text or inline_data or file_data or func call/response ([631b583](https://github.com/google/adk-python/commit/631b58336d36bfd93e190582be34069613d38559))
+* Fixes double response processing issue in `base_llm_flow.py` where, in Bidi-streaming (live) mode, the multi-agent structure causes duplicated responses after tool calling. ([cf21ca3](https://github.com/google/adk-python/commit/cf21ca358478919207049695ba6b31dc6e0b2673))
+* Fix out of bounds error in _run_async_impl ([8fc6128](https://github.com/google/adk-python/commit/8fc6128b62ba576480d196d4a2597564fd0a7006))
+* Fix paths for public docs ([cd54f48](https://github.com/google/adk-python/commit/cd54f48fed0c87b54fb19743c9c75e790c5d9135))
+* Ensure request bodies without explicit names are named 'body' ([084c2de](https://github.com/google/adk-python/commit/084c2de0dac84697906e2b4beebf008bbd9ae8e1)), closes [#2213](https://github.com/google/adk-python/issues/2213)
+* Optimize Stale Agent with GraphQL and Search API to resolve 429 Quota errors ([cb19d07](https://github.com/google/adk-python/commit/cb19d0714c90cd578551753680f39d8d6076c79b))
+* Update AgentTool to use Agent's description when input_schema is provided in FunctionDeclaration ([52674e7](https://github.com/google/adk-python/commit/52674e7fac6b7689f0e3871d41c4523e13471a7e))
+* Update LiteLLM system instruction role from "developer" to "system" ([2e1f730](https://github.com/google/adk-python/commit/2e1f730c3bc0eb454b76d7f36b7b9f1da7304cfe)), closes [#3657](https://github.com/google/adk-python/issues/3657)
+* Update session last update time when appending events ([a3e4ad3](https://github.com/google/adk-python/commit/a3e4ad3cd130714affcaa880f696aeb498cd93af)), closes [#2721](https://github.com/google/adk-python/issues/2721)
+* Update the retry_on_closed_resource decorator to retry on all errors ([a3aa077](https://github.com/google/adk-python/commit/a3aa07722a7de3e08807e86fd10f28938f0b267d))
+* Windows Path Handling and Normalize Cross-Platform Path Resolution in AgentLoader ([a1c09b7](https://github.com/google/adk-python/commit/a1c09b724bb37513eaabaff9643eeaa68014f14d))
+
+
+### Documentation
+
+* Add Code Wiki badge to README ([caf23ac](https://github.com/google/adk-python/commit/caf23ac49fe08bc7f625c61eed4635c26852c3ba))
+
+
 ## [1.19.0](https://github.com/google/adk-python/compare/v1.18.0...v1.19.0) (2025-11-19)
 
 ### Features
diff --git a/src/google/adk/version.py b/src/google/adk/version.py
index 9478b2a5..a287db28 100644
--- a/src/google/adk/version.py
+++ b/src/google/adk/version.py
@@ -13,4 +13,4 @@
 # limitations under the License.
 
 # version: major.minor.patch
-__version__ = "1.19.0"
+__version__ = "1.20.0"