diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c554f9d4..9f964a34 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -25,7 +25,7 @@ jobs:
         with:
           python-version: ${{ matrix.python }}
       - run: python -m pip install --upgrade wheel poetry poethepoet
-      - run: poetry install
+      - run: poetry install --with pydantic
       - run: poe lint
       - run: poe test -s -o log_cli_level=DEBUG
       - run: poe test -s -o log_cli_level=DEBUG --workflow-environment time-skipping
diff --git a/README.md b/README.md
index 268e727b..8bc36863 100644
--- a/README.md
+++ b/README.md
@@ -54,6 +54,7 @@ Some examples require extra dependencies. See each sample's directory for specif
 * [custom_decorator](custom_decorator) - Custom decorator to auto-heartbeat a long-running activity.
 * [encryption](encryption) - Apply end-to-end encryption for all input/output.
 * [open_telemetry](open_telemetry) - Trace workflows with OpenTelemetry.
+* [pydantic_converter](pydantic_converter) - Data converter for using Pydantic models.
 * [sentry](sentry) - Report errors to Sentry.
 
 ## Test
diff --git a/poetry.lock b/poetry.lock
index a82bbeac..6b51ef9f 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -380,6 +380,21 @@ category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 
+[[package]]
+name = "pydantic"
+version = "1.10.4"
+description = "Data validation and settings management using python type hints"
+category = "dev"
+optional = false
+python-versions = ">=3.7"
+
+[package.dependencies]
+typing-extensions = ">=4.2.0"
+
+[package.extras]
+dotenv = ["python-dotenv (>=0.10.4)"]
+email = ["email-validator (>=1.0.3)"]
+
 [[package]]
 name = "pyparsing"
 version = "3.0.9"
@@ -609,7 +624,7 @@ testing = ["flake8 (<5)", "func-timeout", "jaraco.functools", "jaraco.itertools"
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.7"
-content-hash = "8a2f56bce06a187e2b34cee8c69042025c980c47a3869a713f51d15dc50e8da8"
+content-hash = "f47fea5c8855978e7f42535db6f68571393ce360a0a9c30492ce44eb0f93cdf9"
 
 [metadata.files]
 aiohttp = [
@@ -1077,6 +1092,44 @@ pycparser = [
     {file = "pycparser-2.21-py2.py3-none-any.whl", hash = "sha256:8ee45429555515e1f6b185e78100aea234072576aa43ab53aefcae078162fca9"},
     {file = "pycparser-2.21.tar.gz", hash = "sha256:e644fdec12f7872f86c58ff790da456218b10f863970249516d60a5eaca77206"},
 ]
+pydantic = [
+    {file = "pydantic-1.10.4-cp310-cp310-macosx_10_9_x86_64.whl", hash = "sha256:b5635de53e6686fe7a44b5cf25fcc419a0d5e5c1a1efe73d49d48fe7586db854"},
+    {file = "pydantic-1.10.4-cp310-cp310-macosx_11_0_arm64.whl", hash = "sha256:6dc1cc241440ed7ca9ab59d9929075445da6b7c94ced281b3dd4cfe6c8cff817"},
+    {file = "pydantic-1.10.4-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:51bdeb10d2db0f288e71d49c9cefa609bca271720ecd0c58009bd7504a0c464c"},
+    {file = "pydantic-1.10.4-cp310-cp310-manylinux_2_5_i686.manylinux1_i686.manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:78cec42b95dbb500a1f7120bdf95c401f6abb616bbe8785ef09887306792e66e"},
+    {file = "pydantic-1.10.4-cp310-cp310-musllinux_1_1_i686.whl", hash = "sha256:8775d4ef5e7299a2f4699501077a0defdaac5b6c4321173bcb0f3c496fbadf85"},
+    {file = "pydantic-1.10.4-cp310-cp310-musllinux_1_1_x86_64.whl", hash = "sha256:572066051eeac73d23f95ba9a71349c42a3e05999d0ee1572b7860235b850cc6"},
+    {file = "pydantic-1.10.4-cp310-cp310-win_amd64.whl", hash = "sha256:7feb6a2d401f4d6863050f58325b8d99c1e56f4512d98b11ac64ad1751dc647d"},
+    {file = "pydantic-1.10.4-cp311-cp311-macosx_10_9_x86_64.whl", hash = "sha256:39f4a73e5342b25c2959529f07f026ef58147249f9b7431e1ba8414a36761f53"},
+    {file = "pydantic-1.10.4-cp311-cp311-macosx_11_0_arm64.whl", hash = "sha256:983e720704431a6573d626b00662eb78a07148c9115129f9b4351091ec95ecc3"},
+    {file = "pydantic-1.10.4-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:75d52162fe6b2b55964fbb0af2ee58e99791a3138588c482572bb6087953113a"},
+    {file = "pydantic-1.10.4-cp311-cp311-manylinux_2_5_i686.manylinux1_i686.manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:fdf8d759ef326962b4678d89e275ffc55b7ce59d917d9f72233762061fd04a2d"},
+    {file = "pydantic-1.10.4-cp311-cp311-musllinux_1_1_i686.whl", hash = "sha256:05a81b006be15655b2a1bae5faa4280cf7c81d0e09fcb49b342ebf826abe5a72"},
+    {file = "pydantic-1.10.4-cp311-cp311-musllinux_1_1_x86_64.whl", hash = "sha256:d88c4c0e5c5dfd05092a4b271282ef0588e5f4aaf345778056fc5259ba098857"},
+    {file = "pydantic-1.10.4-cp311-cp311-win_amd64.whl", hash = "sha256:6a05a9db1ef5be0fe63e988f9617ca2551013f55000289c671f71ec16f4985e3"},
+    {file = "pydantic-1.10.4-cp37-cp37m-macosx_10_9_x86_64.whl", hash = "sha256:887ca463c3bc47103c123bc06919c86720e80e1214aab79e9b779cda0ff92a00"},
+    {file = "pydantic-1.10.4-cp37-cp37m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:fdf88ab63c3ee282c76d652fc86518aacb737ff35796023fae56a65ced1a5978"},
+    {file = "pydantic-1.10.4-cp37-cp37m-manylinux_2_5_i686.manylinux1_i686.manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:a48f1953c4a1d9bd0b5167ac50da9a79f6072c63c4cef4cf2a3736994903583e"},
+    {file = "pydantic-1.10.4-cp37-cp37m-musllinux_1_1_i686.whl", hash = "sha256:a9f2de23bec87ff306aef658384b02aa7c32389766af3c5dee9ce33e80222dfa"},
+    {file = "pydantic-1.10.4-cp37-cp37m-musllinux_1_1_x86_64.whl", hash = "sha256:cd8702c5142afda03dc2b1ee6bc358b62b3735b2cce53fc77b31ca9f728e4bc8"},
+    {file = "pydantic-1.10.4-cp37-cp37m-win_amd64.whl", hash = "sha256:6e7124d6855b2780611d9f5e1e145e86667eaa3bd9459192c8dc1a097f5e9903"},
+    {file = "pydantic-1.10.4-cp38-cp38-macosx_10_9_x86_64.whl", hash = "sha256:0b53e1d41e97063d51a02821b80538053ee4608b9a181c1005441f1673c55423"},
+    {file = "pydantic-1.10.4-cp38-cp38-macosx_11_0_arm64.whl", hash = "sha256:55b1625899acd33229c4352ce0ae54038529b412bd51c4915349b49ca575258f"},
+    {file = "pydantic-1.10.4-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:301d626a59edbe5dfb48fcae245896379a450d04baeed50ef40d8199f2733b06"},
+    {file = "pydantic-1.10.4-cp38-cp38-manylinux_2_5_i686.manylinux1_i686.manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:b6f9d649892a6f54a39ed56b8dfd5e08b5f3be5f893da430bed76975f3735d15"},
+    {file = "pydantic-1.10.4-cp38-cp38-musllinux_1_1_i686.whl", hash = "sha256:d7b5a3821225f5c43496c324b0d6875fde910a1c2933d726a743ce328fbb2a8c"},
+    {file = "pydantic-1.10.4-cp38-cp38-musllinux_1_1_x86_64.whl", hash = "sha256:f2f7eb6273dd12472d7f218e1fef6f7c7c2f00ac2e1ecde4db8824c457300416"},
+    {file = "pydantic-1.10.4-cp38-cp38-win_amd64.whl", hash = "sha256:4b05697738e7d2040696b0a66d9f0a10bec0efa1883ca75ee9e55baf511909d6"},
+    {file = "pydantic-1.10.4-cp39-cp39-macosx_10_9_x86_64.whl", hash = "sha256:a9a6747cac06c2beb466064dda999a13176b23535e4c496c9d48e6406f92d42d"},
+    {file = "pydantic-1.10.4-cp39-cp39-macosx_11_0_arm64.whl", hash = "sha256:eb992a1ef739cc7b543576337bebfc62c0e6567434e522e97291b251a41dad7f"},
+    {file = "pydantic-1.10.4-cp39-cp39-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:990406d226dea0e8f25f643b370224771878142155b879784ce89f633541a024"},
+    {file = "pydantic-1.10.4-cp39-cp39-manylinux_2_5_i686.manylinux1_i686.manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:2e82a6d37a95e0b1b42b82ab340ada3963aea1317fd7f888bb6b9dfbf4fff57c"},
+    {file = "pydantic-1.10.4-cp39-cp39-musllinux_1_1_i686.whl", hash = "sha256:9193d4f4ee8feca58bc56c8306bcb820f5c7905fd919e0750acdeeeef0615b28"},
+    {file = "pydantic-1.10.4-cp39-cp39-musllinux_1_1_x86_64.whl", hash = "sha256:2b3ce5f16deb45c472dde1a0ee05619298c864a20cded09c4edd820e1454129f"},
+    {file = "pydantic-1.10.4-cp39-cp39-win_amd64.whl", hash = "sha256:9cbdc268a62d9a98c56e2452d6c41c0263d64a2009aac69246486f01b4f594c4"},
+    {file = "pydantic-1.10.4-py3-none-any.whl", hash = "sha256:4948f264678c703f3877d1c8877c4e3b2e12e549c57795107f08cf70c6ec7774"},
+    {file = "pydantic-1.10.4.tar.gz", hash = "sha256:b9a3859f24eb4e097502a3be1fb4b2abb79b6103dd9e2e0edb70613a4459a648"},
+]
 pyparsing = [
     {file = "pyparsing-3.0.9-py3-none-any.whl", hash = "sha256:5026bae9a10eeaefb61dab2f09052b9f4307d44aee4eda64b309723d8d206bbc"},
     {file = "pyparsing-3.0.9.tar.gz", hash = "sha256:2b020ecf7d21b687f219b71ecad3631f644a47f01403fa1d1036b0c6416d70fb"},
diff --git a/pydantic_converter/README.md b/pydantic_converter/README.md
new file mode 100644
index 00000000..5914fa3d
--- /dev/null
+++ b/pydantic_converter/README.md
@@ -0,0 +1,31 @@
+# Pydantic Converter Sample
+
+This sample shows how to create a custom Pydantic converter to properly serialize Pydantic models.
+
+For this sample, the optional `pydantic` dependency group must be included. To include, run:
+
+    poetry install --with pydantic
+
+To run, first see [README.md](../README.md) for prerequisites. Then, run the following from this directory to start the
+worker:
+
+    poetry run python worker.py
+
+This will start the worker. Then, in another terminal, run the following to execute the workflow:
+
+    poetry run python starter.py
+
+In the worker terminal, the workflow and its activity will log that it received the Pydantic models. In the starter
+terminal, the Pydantic models in the workflow result will be logged.
+
+### Notes
+
+This is the preferred way to use Pydantic models with Temporal Python SDK. The converter code is small and meant to
+embed into other projects.
+
+This sample also demonstrates use of `datetime` inside of Pydantic models. Due to a known issue with the Temporal
+sandbox, this class is seen by Pydantic as `date` instead of `datetime` upon deserialization. This is due to a
+[known Python issue](https://github.com/python/cpython/issues/89010) where, when we proxy the `datetime` class in the
+sandbox to prevent non-deterministic calls like `now()`, `issubclass` fails for the proxy type causing Pydantic to think
+it's a `date` instead. In `worker.py`, we have shown a workaround of disabling restrictions on `datetime` which solves
+this issue but no longer protects against workflow developers making non-deterministic calls in that module.
\ No newline at end of file
diff --git a/pydantic_converter/__init__.py b/pydantic_converter/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/pydantic_converter/converter.py b/pydantic_converter/converter.py
new file mode 100644
index 00000000..a3c1cee6
--- /dev/null
+++ b/pydantic_converter/converter.py
@@ -0,0 +1,56 @@
+import json
+from typing import Any, Optional
+
+from pydantic.json import pydantic_encoder
+from temporalio.api.common.v1 import Payload
+from temporalio.converter import (
+    CompositePayloadConverter,
+    DataConverter,
+    DefaultPayloadConverter,
+    JSONPlainPayloadConverter,
+)
+
+
+class PydanticJSONPayloadConverter(JSONPlainPayloadConverter):
+    """Pydantic JSON payload converter.
+
+    This extends the :py:class:`JSONPlainPayloadConverter` to override
+    :py:meth:`to_payload` using the Pydantic encoder.
+    """
+
+    def to_payload(self, value: Any) -> Optional[Payload]:
+        """Convert all values with Pydantic encoder or fail.
+
+        Like the base class, we fail if we cannot convert. This payload
+        converter is expected to be the last in the chain, so it can fail if
+        unable to convert.
+        """
+        # We let JSON conversion errors be thrown to caller
+        return Payload(
+            metadata={"encoding": self.encoding.encode()},
+            data=json.dumps(
+                value, separators=(",", ":"), sort_keys=True, default=pydantic_encoder
+            ).encode(),
+        )
+
+
+class PydanticPayloadConverter(CompositePayloadConverter):
+    """Payload converter that replaces Temporal JSON conversion with Pydantic
+    JSON conversion.
+    """
+
+    def __init__(self) -> None:
+        super().__init__(
+            *(
+                c
+                if not isinstance(c, JSONPlainPayloadConverter)
+                else PydanticJSONPayloadConverter()
+                for c in DefaultPayloadConverter.default_encoding_payload_converters
+            )
+        )
+
+
+pydantic_data_converter = DataConverter(
+    payload_converter_class=PydanticPayloadConverter
+)
+"""Data converter using Pydantic JSON conversion."""
diff --git a/pydantic_converter/starter.py b/pydantic_converter/starter.py
new file mode 100644
index 00000000..5aceca6e
--- /dev/null
+++ b/pydantic_converter/starter.py
@@ -0,0 +1,39 @@
+import asyncio
+import logging
+from datetime import datetime
+from ipaddress import IPv4Address
+
+from temporalio.client import Client
+
+from pydantic_converter.converter import pydantic_data_converter
+from pydantic_converter.worker import MyPydanticModel, MyWorkflow
+
+
+async def main():
+    logging.basicConfig(level=logging.INFO)
+    # Connect client using the Pydantic converter
+    client = await Client.connect(
+        "localhost:7233", data_converter=pydantic_data_converter
+    )
+
+    # Run workflow
+    result = await client.execute_workflow(
+        MyWorkflow.run,
+        [
+            MyPydanticModel(
+                some_ip=IPv4Address("127.0.0.1"),
+                some_date=datetime(2000, 1, 2, 3, 4, 5),
+            ),
+            MyPydanticModel(
+                some_ip=IPv4Address("127.0.0.2"),
+                some_date=datetime(2001, 2, 3, 4, 5, 6),
+            ),
+        ],
+        id=f"pydantic_converter-workflow-id",
+        task_queue="pydantic_converter-task-queue",
+    )
+    logging.info("Got models from client: %s" % result)
+
+
+if __name__ == "__main__":
+    asyncio.run(main())
diff --git a/pydantic_converter/worker.py b/pydantic_converter/worker.py
new file mode 100644
index 00000000..b7e0bedf
--- /dev/null
+++ b/pydantic_converter/worker.py
@@ -0,0 +1,98 @@
+import asyncio
+import dataclasses
+import logging
+from datetime import datetime, timedelta
+from ipaddress import IPv4Address
+from typing import List
+
+from temporalio import activity, workflow
+from temporalio.client import Client
+from temporalio.worker import Worker
+from temporalio.worker.workflow_sandbox import (
+    SandboxedWorkflowRunner,
+    SandboxRestrictions,
+)
+
+# We always want to pass through external modules to the sandbox that we know
+# are safe for workflow use
+with workflow.unsafe.imports_passed_through():
+    from pydantic import BaseModel
+
+    from pydantic_converter.converter import pydantic_data_converter
+
+
+class MyPydanticModel(BaseModel):
+    some_ip: IPv4Address
+    some_date: datetime
+
+
+@activity.defn
+async def my_activity(models: List[MyPydanticModel]) -> List[MyPydanticModel]:
+    activity.logger.info("Got models in activity: %s" % models)
+    return models
+
+
+@workflow.defn
+class MyWorkflow:
+    @workflow.run
+    async def run(self, models: List[MyPydanticModel]) -> List[MyPydanticModel]:
+        workflow.logger.info("Got models in workflow: %s" % models)
+        return await workflow.execute_activity(
+            my_activity, models, start_to_close_timeout=timedelta(minutes=1)
+        )
+
+
+# Due to known issues with Pydantic's use of issubclass and our inability to
+# override the check in sandbox, Pydantic will think datetime is actually date
+# in the sandbox. At the expense of protecting against datetime.now() use in
+# workflows, we're going to remove datetime module restrictions. See sdk-python
+# README's discussion of known sandbox issues for more details.
+def new_sandbox_runner() -> SandboxedWorkflowRunner:
+    # TODO(cretz): Use with_child_unrestricted when https://github.com/temporalio/sdk-python/issues/254
+    # is fixed and released
+    invalid_module_member_children = dict(
+        SandboxRestrictions.invalid_module_members_default.children
+    )
+    del invalid_module_member_children["datetime"]
+    return SandboxedWorkflowRunner(
+        restrictions=dataclasses.replace(
+            SandboxRestrictions.default,
+            invalid_module_members=dataclasses.replace(
+                SandboxRestrictions.invalid_module_members_default,
+                children=invalid_module_member_children,
+            ),
+        )
+    )
+
+
+interrupt_event = asyncio.Event()
+
+
+async def main():
+    logging.basicConfig(level=logging.INFO)
+    # Connect client using the Pydantic converter
+    client = await Client.connect(
+        "localhost:7233", data_converter=pydantic_data_converter
+    )
+
+    # Run a worker for the workflow
+    async with Worker(
+        client,
+        task_queue="pydantic_converter-task-queue",
+        workflows=[MyWorkflow],
+        activities=[my_activity],
+        workflow_runner=new_sandbox_runner(),
+    ):
+        # Wait until interrupted
+        print("Worker started, ctrl+c to exit")
+        await interrupt_event.wait()
+        print("Shutting down")
+
+
+if __name__ == "__main__":
+    loop = asyncio.new_event_loop()
+    try:
+        loop.run_until_complete(main())
+    except KeyboardInterrupt:
+        interrupt_event.set()
+        loop.run_until_complete(loop.shutdown_asyncgens())
diff --git a/pyproject.toml b/pyproject.toml
index 57c1c6fe..bf621774 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -39,6 +39,10 @@ optional = true
 temporalio = { version = "*", extras = ["opentelemetry"] }
 opentelemetry-exporter-jaeger-thrift = "^1.13.0"
 
+[tool.poetry.group.pydantic]
+optional = true
+dependencies = { pydantic = "^1.10.4" }
+
 [tool.poetry.group.sentry]
 optional = true
 dependencies = { sentry-sdk = "^1.11.0" }
@@ -46,7 +50,7 @@ dependencies = { sentry-sdk = "^1.11.0" }
 [tool.poe.tasks]
 format = [{cmd = "black ."}, {cmd = "isort ."}]
 lint = [{cmd = "black --check ."}, {cmd = "isort --check-only ."}, {ref = "lint-types" }]
-lint-types = "mypy --check-untyped-defs ."
+lint-types = "mypy --check-untyped-defs --namespace-packages ."
 test = "pytest"
 
 [build-system]
diff --git a/tests/pydantic_converter/__init__.py b/tests/pydantic_converter/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/pydantic_converter/workflow_test.py b/tests/pydantic_converter/workflow_test.py
new file mode 100644
index 00000000..a547caf0
--- /dev/null
+++ b/tests/pydantic_converter/workflow_test.py
@@ -0,0 +1,46 @@
+import uuid
+from datetime import datetime
+from ipaddress import IPv4Address
+
+from temporalio.client import Client
+from temporalio.worker import Worker
+
+from pydantic_converter.converter import pydantic_data_converter
+from pydantic_converter.worker import (
+    MyPydanticModel,
+    MyWorkflow,
+    my_activity,
+    new_sandbox_runner,
+)
+
+
+async def test_workflow_with_pydantic_model(client: Client):
+    # Replace data converter in client
+    new_config = client.config()
+    new_config["data_converter"] = pydantic_data_converter
+    client = Client(**new_config)
+    task_queue_name = str(uuid.uuid4())
+
+    orig_models = [
+        MyPydanticModel(
+            some_ip=IPv4Address("127.0.0.1"), some_date=datetime(2000, 1, 2, 3, 4, 5)
+        ),
+        MyPydanticModel(
+            some_ip=IPv4Address("127.0.0.2"), some_date=datetime(2001, 2, 3, 4, 5, 6)
+        ),
+    ]
+
+    async with Worker(
+        client,
+        task_queue=task_queue_name,
+        workflows=[MyWorkflow],
+        activities=[my_activity],
+        workflow_runner=new_sandbox_runner(),
+    ):
+        result = await client.execute_workflow(
+            MyWorkflow.run,
+            orig_models,
+            id=str(uuid.uuid4()),
+            task_queue=task_queue_name,
+        )
+    assert orig_models == result