diff --git a/src/google/adk/plugins/context_filter_plugin.py b/src/google/adk/plugins/context_filter_plugin.py
new file mode 100644
index 00000000..b778de02
--- /dev/null
+++ b/src/google/adk/plugins/context_filter_plugin.py
@@ -0,0 +1,88 @@
+# Copyright 2025 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.
+
+from __future__ import annotations
+
+import logging
+from typing import Callable
+from typing import List
+from typing import Optional
+
+from ..agents.callback_context import CallbackContext
+from ..events.event import Event
+from ..models.llm_request import LlmRequest
+from ..models.llm_response import LlmResponse
+from .base_plugin import BasePlugin
+
+logger = logging.getLogger("google_adk." + __name__)
+
+
+class ContextFilterPlugin(BasePlugin):
+  """A plugin that filters the LLM context to reduce its size."""
+
+  def __init__(
+      self,
+      num_invocations_to_keep: Optional[int] = None,
+      custom_filter: Optional[Callable[[List[Event]], List[Event]]] = None,
+      name: str = "context_filter_plugin",
+  ):
+    """Initializes the context management plugin.
+
+    Args:
+      num_invocations_to_keep: The number of last invocations to keep. An
+        invocation is defined as one or more consecutive user messages followed
+        by a model response.
+      custom_filter: A function to filter the context.
+      name: The name of the plugin instance.
+    """
+    super().__init__(name)
+    self._num_invocations_to_keep = num_invocations_to_keep
+    self._custom_filter = custom_filter
+
+  async def before_model_callback(
+      self, *, callback_context: CallbackContext, llm_request: LlmRequest
+  ) -> Optional[LlmResponse]:
+    """Filters the LLM request's context before it is sent to the model."""
+    try:
+      contents = llm_request.contents
+
+      if (
+          self._num_invocations_to_keep is not None
+          and self._num_invocations_to_keep > 0
+      ):
+        num_model_turns = sum(1 for c in contents if c.role == "model")
+        if num_model_turns >= self._num_invocations_to_keep:
+          model_turns_to_find = self._num_invocations_to_keep
+          split_index = 0
+          for i in range(len(contents) - 1, -1, -1):
+            if contents[i].role == "model":
+              model_turns_to_find -= 1
+              if model_turns_to_find == 0:
+                start_index = i
+                while (
+                    start_index > 0 and contents[start_index - 1].role == "user"
+                ):
+                  start_index -= 1
+                split_index = start_index
+                break
+          contents = contents[split_index:]
+
+      if self._custom_filter:
+        contents = self._custom_filter(contents)
+
+      llm_request.contents = contents
+    except Exception as e:
+      logger.error(f"Failed to reduce context for request: {e}")
+
+    return None
diff --git a/tests/unittests/plugins/test_context_filtering_plugin.py b/tests/unittests/plugins/test_context_filtering_plugin.py
new file mode 100644
index 00000000..f9c8222e
--- /dev/null
+++ b/tests/unittests/plugins/test_context_filtering_plugin.py
@@ -0,0 +1,185 @@
+# Copyright 2025 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.
+
+"""Unit tests for the ContextFilteringPlugin."""
+
+from unittest.mock import Mock
+
+from google.adk.agents.callback_context import CallbackContext
+from google.adk.models.llm_request import LlmRequest
+from google.adk.plugins.context_filter_plugin import ContextFilterPlugin
+from google.genai import types
+import pytest
+
+
+def _create_content(role: str, text: str) -> types.Content:
+  return types.Content(parts=[types.Part(text=text)], role=role)
+
+
+@pytest.mark.asyncio
+async def test_filter_last_n_invocations():
+  """Tests that the context is truncated to the last N invocations."""
+  plugin = ContextFilterPlugin(num_invocations_to_keep=1)
+  contents = [
+      _create_content("user", "user_prompt_1"),
+      _create_content("model", "model_response_1"),
+      _create_content("user", "user_prompt_2"),
+      _create_content("model", "model_response_2"),
+  ]
+  llm_request = LlmRequest(contents=contents)
+
+  await plugin.before_model_callback(
+      callback_context=Mock(spec=CallbackContext), llm_request=llm_request
+  )
+
+  assert len(llm_request.contents) == 2
+  assert llm_request.contents[0].parts[0].text == "user_prompt_2"
+  assert llm_request.contents[1].parts[0].text == "model_response_2"
+
+
+@pytest.mark.asyncio
+async def test_filter_with_function():
+  """Tests that a custom filter function is applied to the context."""
+
+  def remove_model_responses(contents):
+    return [c for c in contents if c.role != "model"]
+
+  plugin = ContextFilterPlugin(custom_filter=remove_model_responses)
+  contents = [
+      _create_content("user", "user_prompt_1"),
+      _create_content("model", "model_response_1"),
+      _create_content("user", "user_prompt_2"),
+      _create_content("model", "model_response_2"),
+  ]
+  llm_request = LlmRequest(contents=contents)
+
+  await plugin.before_model_callback(
+      callback_context=Mock(spec=CallbackContext), llm_request=llm_request
+  )
+
+  assert len(llm_request.contents) == 2
+  assert all(c.role == "user" for c in llm_request.contents)
+
+
+@pytest.mark.asyncio
+async def test_filter_with_function_and_last_n_invocations():
+  """Tests that both filtering methods are applied correctly."""
+
+  def remove_first_invocation(contents):
+    return contents[2:]
+
+  plugin = ContextFilterPlugin(
+      num_invocations_to_keep=1, custom_filter=remove_first_invocation
+  )
+  contents = [
+      _create_content("user", "user_prompt_1"),
+      _create_content("model", "model_response_1"),
+      _create_content("user", "user_prompt_2"),
+      _create_content("model", "model_response_2"),
+      _create_content("user", "user_prompt_3"),
+      _create_content("model", "model_response_3"),
+  ]
+  llm_request = LlmRequest(contents=contents)
+
+  await plugin.before_model_callback(
+      callback_context=Mock(spec=CallbackContext), llm_request=llm_request
+  )
+
+  assert len(llm_request.contents) == 0
+
+
+@pytest.mark.asyncio
+async def test_no_filtering_when_no_options_provided():
+  """Tests that no filtering occurs when no options are provided."""
+  plugin = ContextFilterPlugin()
+  contents = [
+      _create_content("user", "user_prompt_1"),
+      _create_content("model", "model_response_1"),
+  ]
+  llm_request = LlmRequest(contents=contents)
+  original_contents = list(llm_request.contents)
+
+  await plugin.before_model_callback(
+      callback_context=Mock(spec=CallbackContext), llm_request=llm_request
+  )
+
+  assert llm_request.contents == original_contents
+
+
+@pytest.mark.asyncio
+async def test_last_n_invocations_with_multiple_user_turns():
+  """Tests filtering with multiple user turns in a single invocation."""
+  plugin = ContextFilterPlugin(num_invocations_to_keep=1)
+  contents = [
+      _create_content("user", "user_prompt_1"),
+      _create_content("model", "model_response_1"),
+      _create_content("user", "user_prompt_2a"),
+      _create_content("user", "user_prompt_2b"),
+      _create_content("model", "model_response_2"),
+  ]
+  llm_request = LlmRequest(contents=contents)
+
+  await plugin.before_model_callback(
+      callback_context=Mock(spec=CallbackContext), llm_request=llm_request
+  )
+
+  assert len(llm_request.contents) == 3
+  assert llm_request.contents[0].parts[0].text == "user_prompt_2a"
+  assert llm_request.contents[1].parts[0].text == "user_prompt_2b"
+  assert llm_request.contents[2].parts[0].text == "model_response_2"
+
+
+@pytest.mark.asyncio
+async def test_last_n_invocations_more_than_existing_invocations():
+  """Tests that no filtering occurs if last_n_invocations is greater than
+
+  the number of invocations.
+  """
+  plugin = ContextFilterPlugin(num_invocations_to_keep=3)
+  contents = [
+      _create_content("user", "user_prompt_1"),
+      _create_content("model", "model_response_1"),
+      _create_content("user", "user_prompt_2"),
+      _create_content("model", "model_response_2"),
+  ]
+  llm_request = LlmRequest(contents=contents)
+  original_contents = list(llm_request.contents)
+
+  await plugin.before_model_callback(
+      callback_context=Mock(spec=CallbackContext), llm_request=llm_request
+  )
+
+  assert llm_request.contents == original_contents
+
+
+@pytest.mark.asyncio
+async def test_filter_function_raises_exception():
+  """Tests that the plugin handles exceptions from the filter function."""
+
+  def faulty_filter(contents):
+    raise ValueError("Filter error")
+
+  plugin = ContextFilterPlugin(custom_filter=faulty_filter)
+  contents = [
+      _create_content("user", "user_prompt_1"),
+      _create_content("model", "model_response_1"),
+  ]
+  llm_request = LlmRequest(contents=contents)
+  original_contents = list(llm_request.contents)
+
+  await plugin.before_model_callback(
+      callback_context=Mock(spec=CallbackContext), llm_request=llm_request
+  )
+
+  assert llm_request.contents == original_contents