diff --git a/python/langsmith/client.py b/python/langsmith/client.py
index 2596e4d7c..cc50e2b78 100644
--- a/python/langsmith/client.py
+++ b/python/langsmith/client.py
@@ -20,6 +20,7 @@
     AsyncGenerator,
     AsyncIterator,
     Callable,
+    Coroutine,
     DefaultDict,
     Dict,
     Iterable,
@@ -129,7 +130,44 @@ def close_client(client: httpx.Client) -> None:
 
 def close_async_client(client: httpx.AsyncClient) -> None:
     logger.debug("Closing Client._aclient")
-    asyncio.run(client.aclose())
+    coro = client.aclose()
+    try:
+        # Raises RuntimeError if there is no current event loop.
+        asyncio.get_running_loop()
+        loop_running = True
+    except RuntimeError:
+        loop_running = False
+
+    if loop_running:
+        # If we try to submit this coroutine to the running loop
+        # we end up in a deadlock, as we'd have gotten here from a
+        # running coroutine, which we cannot interrupt to run this one.
+        # The solution is to create a new loop in a new thread.
+        with concurrent.futures.ThreadPoolExecutor(1) as executor:
+            executor.submit(_run_coros, coro).result()
+    else:
+        _run_coros(coro)
+
+
+def _run_coros(coro: Coroutine) -> None:
+    if hasattr(asyncio, "Runner"):
+        # Python 3.11+
+        # Run the coroutines in a new event loop, taking care to
+        # - install signal handlers
+        # - run pending tasks scheduled by `coros`
+        # - close asyncgens and executors
+        # - close the loop
+        with asyncio.Runner() as runner:
+            # Run the coroutine, get the result
+            runner.run(coro)
+
+            # Run pending tasks scheduled by coros until they are all done
+            while pending := asyncio.all_tasks(runner.get_loop()):
+                runner.run(asyncio.wait(pending))
+    else:
+        # Before Python 3.11 we need to run each coroutine in a new event loop
+        # as the Runner api is not available.
+        asyncio.run(coro)
 
 
 def _validate_api_key_if_hosted(api_url: str, api_key: Optional[str]) -> None:
@@ -1247,7 +1285,7 @@ def _prepare_create_project(
         project_extra: Optional[dict] = None,
         upsert: bool = False,
         reference_dataset_id: Optional[ID_TYPE] = None,
-    ) -> ls_schemas.TracerSession:
+    ) -> dict:
         """Create a project on the LangSmith API.
 
         Parameters
diff --git a/python/tests/integration_tests/test_client_async.py b/python/tests/integration_tests/test_client_async.py
new file mode 100644
index 000000000..89823e23b
--- /dev/null
+++ b/python/tests/integration_tests/test_client_async.py
@@ -0,0 +1,178 @@
+"""LangSmith langchain_client Integration Tests."""
+import os
+from datetime import datetime
+from uuid import uuid4
+
+import pytest
+import requests
+from freezegun import freeze_time
+
+from langsmith.client import Client
+from langsmith.utils import LangSmithConnectionError, LangSmithError
+
+
+@pytest.fixture
+def langchain_client(monkeypatch: pytest.MonkeyPatch) -> Client:
+    monkeypatch.setenv("LANGCHAIN_ENDPOINT", "http://localhost:1984")
+    return Client()
+
+
+@pytest.mark.asyncio
+async def test_projects(
+    langchain_client: Client, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """Test projects."""
+    project_names = set([project.name for project in langchain_client.list_projects()])
+    new_project = "__Test Project"
+    if new_project in project_names:
+        langchain_client.delete_project(project_name=new_project)
+        project_names = set(
+            [project.name for project in langchain_client.list_projects()]
+        )
+    assert new_project not in project_names
+
+    monkeypatch.setenv("LANGCHAIN_ENDPOINT", "http://localhost:1984")
+    await langchain_client.acreate_project(
+        project_name=new_project,
+        project_extra={"evaluator": "THE EVALUATOR"},
+    )
+    project = await langchain_client.aread_project(project_name=new_project)
+    assert project.name == new_project
+    project_names = set([sess.name for sess in langchain_client.list_projects()])
+    assert new_project in project_names
+    runs = [run async for run in langchain_client.alist_runs(project_name=new_project)]
+    project_id_runs = [
+        run async for run in langchain_client.alist_runs(project_id=project.id)
+    ]
+    assert len(runs) == len(project_id_runs) == 0  # TODO: Add create_run method
+    langchain_client.delete_project(project_name=new_project)
+
+    with pytest.raises(LangSmithError):
+        await langchain_client.aread_project(project_name=new_project)
+    assert new_project not in set(
+        [sess.name for sess in langchain_client.list_projects()]
+    )
+    with pytest.raises(LangSmithError):
+        langchain_client.delete_project(project_name=new_project)
+
+
+@pytest.mark.asyncio
+@freeze_time("2023-01-01")
+async def test_persist_update_run(
+    monkeypatch: pytest.MonkeyPatch, langchain_client: Client
+) -> None:
+    """Test the persist and update methods work as expected."""
+    monkeypatch.setenv("LANGCHAIN_ENDPOINT", "http://localhost:1984")
+    project_name = "__test_persist_update_run"
+    if project_name in [sess.name for sess in langchain_client.list_projects()]:
+        langchain_client.delete_project(project_name=project_name)
+    start_time = datetime.now()
+    run: dict = dict(
+        id=uuid4(),
+        name="test_run",
+        run_type="llm",
+        inputs={"text": "hello world"},
+        project_name=project_name,
+        api_url=os.getenv("LANGCHAIN_ENDPOINT"),
+        execution_order=1,
+        start_time=start_time,
+        extra={"extra": "extra"},
+    )
+    await langchain_client.acreate_run(**run)
+    run["outputs"] = {"output": ["Hi"]}
+    run["extra"]["foo"] = "bar"
+    await langchain_client.aupdate_run(run["id"], **run)
+    stored_run = await langchain_client.aread_run(run["id"])
+    assert stored_run.id == run["id"]
+    assert stored_run.outputs == run["outputs"]
+    assert stored_run.start_time == run["start_time"]
+    langchain_client.delete_project(project_name=project_name)
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("uri", ["http://localhost:1981", "http://api.langchain.minus"])
+async def test_error_surfaced_invalid_uri(
+    monkeypatch: pytest.MonkeyPatch, uri: str
+) -> None:
+    monkeypatch.setenv("LANGCHAIN_ENDPOINT", uri)
+    monkeypatch.setenv("LANGCHAIN_API_KEY", "test")
+    client = Client()
+    # expect connect error
+    with pytest.raises(LangSmithConnectionError):
+        await client.acreate_run(
+            "My Run", inputs={"text": "hello world"}, run_type="llm"
+        )
+
+
+@pytest.mark.asyncio
+@freeze_time("2023-01-01")
+async def test_share_unshare_run(
+    monkeypatch: pytest.MonkeyPatch, langchain_client: Client
+) -> None:
+    """Test persisting runs and adding feedback."""
+    monkeypatch.setenv("LANGCHAIN_ENDPOINT", "http://localhost:1984")
+    run_id = uuid4()
+    await langchain_client.acreate_run(
+        name="Test run",
+        inputs={"input": "hello world"},
+        run_type="chain",
+        id=run_id,
+    )
+    shared_url = await langchain_client.ashare_run(run_id)
+    response = requests.get(shared_url)
+    assert response.status_code == 200
+    assert await langchain_client.aread_run_shared_link(run_id) == shared_url
+    await langchain_client.aunshare_run(run_id)
+
+
+@pytest.mark.asyncio
+@freeze_time("2023-01-01")
+async def test_create_run_with_masked_inputs_outputs(
+    langchain_client: Client, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    project_name = "__test_create_run_with_masked_inputs_outputs"
+    monkeypatch.setenv("LANGCHAIN_HIDE_INPUTS", "true")
+    monkeypatch.setenv("LANGCHAIN_HIDE_OUTPUTS", "true")
+    for project in langchain_client.list_projects():
+        if project.name == project_name:
+            langchain_client.delete_project(project_name=project_name)
+
+    run_id = "8bac165f-470e-4bf8-baa0-15f2de4cc706"
+    await langchain_client.acreate_run(
+        id=run_id,
+        project_name=project_name,
+        name="test_run",
+        run_type="llm",
+        inputs={"prompt": "hello world"},
+        outputs={"generation": "hi there"},
+        start_time=datetime.utcnow(),
+        end_time=datetime.utcnow(),
+        hide_inputs=True,
+        hide_outputs=True,
+    )
+
+    run_id2 = "8bac165f-490e-4bf8-baa0-15f2de4cc707"
+    await langchain_client.acreate_run(
+        id=run_id2,
+        project_name=project_name,
+        name="test_run_2",
+        run_type="llm",
+        inputs={"messages": "hello world 2"},
+        start_time=datetime.utcnow(),
+        hide_inputs=True,
+    )
+
+    await langchain_client.aupdate_run(
+        run_id2,
+        outputs={"generation": "hi there 2"},
+        end_time=datetime.utcnow(),
+        hide_outputs=True,
+    )
+
+    run1 = await langchain_client.aread_run(run_id)
+    assert run1.inputs == {}
+    assert run1.outputs == {}
+
+    run2 = await langchain_client.aread_run(run_id2)
+    assert run2.inputs == {}
+    assert run2.outputs == {}
diff --git a/python/tests/unit_tests/test_client.py b/python/tests/unit_tests/test_client.py
index ad0ebe266..4b23ea29a 100644
--- a/python/tests/unit_tests/test_client.py
+++ b/python/tests/unit_tests/test_client.py
@@ -7,6 +7,7 @@
 from unittest import mock
 from unittest.mock import patch
 
+import httpx
 import pytest
 
 from langsmith.client import (
@@ -15,6 +16,7 @@
     _get_api_url,
     _is_langchain_hosted,
     _is_localhost,
+    close_async_client,
 )
 from langsmith.schemas import Example
 from langsmith.utils import LangSmithUserError
@@ -53,8 +55,8 @@ def test_headers(monkeypatch: pytest.MonkeyPatch) -> None:
     assert client_no_key._headers == {}
 
 
-@mock.patch("langsmith.client.requests.Session")
-def test_upload_csv(mock_session_cls: mock.Mock) -> None:
+@mock.patch("langsmith.client.httpx.Client")
+def test_upload_csv(mock_client_cls: mock.Mock) -> None:
     dataset_id = str(uuid.uuid4())
     example_1 = Example(
         id=str(uuid.uuid4()),
@@ -79,9 +81,9 @@ def test_upload_csv(mock_session_cls: mock.Mock) -> None:
         "created_at": _CREATED_AT,
         "examples": [example_1, example_2],
     }
-    mock_session = mock.Mock()
-    mock_session.post.return_value = mock_response
-    mock_session_cls.return_value = mock_session
+    mock__client = mock.Mock()
+    mock__client.post.return_value = mock_response
+    mock_client_cls.return_value = mock__client
 
     client = Client(
         api_url="http://localhost:1984",
@@ -174,9 +176,9 @@ def test_create_run_unicode():
         "qux": "나는\u3000밥을\u3000먹었습니다.",
         "는\u3000밥": "나는\u3000밥을\u3000먹었습니다.",
     }
-    session = mock.Mock()
-    session.request = mock.Mock()
-    with patch.object(client, "session", session):
+    _client = mock.Mock()
+    _client.request = mock.Mock()
+    with patch.object(client, "_client", _client):
         id_ = uuid.uuid4()
         client.create_run(
             "my_run", inputs=inputs, run_type="llm", execution_order=1, id=id_
@@ -187,7 +189,7 @@ def test_create_run_unicode():
 @pytest.mark.parametrize("source_type", ["api", "model"])
 def test_create_feedback_string_source_type(source_type: str):
     client = Client(api_url="http://localhost:1984", api_key="123")
-    session = mock.Mock()
+    _client = mock.Mock()
     request_object = mock.Mock()
     request_object.json.return_value = {
         "id": uuid.uuid4(),
@@ -196,11 +198,26 @@ def test_create_feedback_string_source_type(source_type: str):
         "modified_at": _CREATED_AT,
         "run_id": uuid.uuid4(),
     }
-    session.post.return_value = request_object
-    with patch.object(client, "session", session):
+    _client.post.return_value = request_object
+    with patch.object(client, "_client", _client):
         id_ = uuid.uuid4()
         client.create_feedback(
             id_,
             key="Foo",
             feedback_source_type=source_type,
         )
+
+
+@pytest.mark.asyncio
+async def test_close_async_client() -> None:
+    async with httpx.AsyncClient() as client:
+        close_async_client(client)
+        assert client.is_closed
+
+
+@pytest.mark.asyncio
+async def test_close_async_client_in_event_loop() -> None:
+    async with httpx.AsyncClient() as client:
+        loop = asyncio.get_event_loop()
+        await loop.run_in_executor(None, close_async_client, client)
+        assert client.is_closed