diff --git a/python/ray/cluster_utils.py b/python/ray/cluster_utils.py
index f959116e2..64854bc27 100644
--- a/python/ray/cluster_utils.py
+++ b/python/ray/cluster_utils.py
@@ -14,6 +14,8 @@ from ray import ray_constants
 
 logger = logging.getLogger(__name__)
 
+cluster_not_supported = (os.name == "nt")
+
 
 class AutoscalingCluster:
     """Create a local autoscaling cluster for testing.
@@ -102,6 +104,11 @@ class Cluster:
             shutdown_at_exit (bool): If True, registers an exit hook
                 for shutting down all started processes.
         """
+        if cluster_not_supported:
+            logger.warning(
+                "Ray cluster mode is currently experimental and untested on "
+                "Windows. If you are using it and running into issues please "
+                "file a report at https://github.com/ray-project/ray/issues.")
         self.head_node = None
         self.worker_nodes = set()
         self.redis_address = None
diff --git a/python/ray/tests/conftest.py b/python/ray/tests/conftest.py
index 3a1d3aca4..3c7cbc840 100644
--- a/python/ray/tests/conftest.py
+++ b/python/ray/tests/conftest.py
@@ -9,7 +9,8 @@ import json
 import time
 
 import ray
-from ray.cluster_utils import Cluster, AutoscalingCluster
+from ray.cluster_utils import (Cluster, AutoscalingCluster,
+                               cluster_not_supported)
 from ray._private.services import REDIS_EXECUTABLE, _start_redis_instance
 from ray._private.test_utils import (init_error_pubsub, init_log_pubsub,
                                      setup_tls, teardown_tls,
@@ -117,6 +118,8 @@ def ray_start_10_cpus(request):
 
 @contextmanager
 def _ray_start_cluster(**kwargs):
+    if cluster_not_supported:
+        pytest.skip("Cluster not supported")
     init_kwargs = get_default_fixture_ray_kwargs()
     num_nodes = 0
     do_init = False
@@ -290,6 +293,8 @@ def two_node_cluster():
         "object_timeout_milliseconds": 200,
         "num_heartbeats_timeout": 10,
     }
+    if cluster_not_supported:
+        pytest.skip("Cluster not supported")
     cluster = ray.cluster_utils.Cluster(
         head_node_args={"_system_config": system_config})
     for _ in range(2):
diff --git a/python/ray/tests/test_advanced.py b/python/ray/tests/test_advanced.py
index abf6265d2..0b8d56285 100644
--- a/python/ray/tests/test_advanced.py
+++ b/python/ray/tests/test_advanced.py
@@ -371,6 +371,7 @@ def test_illegal_api_calls(ray_start_regular):
 
 @pytest.mark.skipif(
     client_test_enabled(), reason="grpc interaction with releasing resources")
+@pytest.mark.skipif(sys.platform == "win32", reason="Time out on Windows")
 def test_multithreading(ray_start_2_cpus):
     # This test requires at least 2 CPUs to finish since the worker does not
     # release resources when joining the threads.
diff --git a/python/ray/tests/test_asyncio_cluster.py b/python/ray/tests/test_asyncio_cluster.py
index da5689a20..bea440bdf 100644
--- a/python/ray/tests/test_asyncio_cluster.py
+++ b/python/ray/tests/test_asyncio_cluster.py
@@ -6,9 +6,10 @@ import pytest
 import numpy as np
 
 import ray
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 @pytest.mark.asyncio
 async def test_asyncio_cluster_wait():
     cluster = Cluster()
diff --git a/python/ray/tests/test_basic_2.py b/python/ray/tests/test_basic_2.py
index f57e645dc..7ca663c1e 100644
--- a/python/ray/tests/test_basic_2.py
+++ b/python/ray/tests/test_basic_2.py
@@ -12,7 +12,7 @@ import pytest
 
 from unittest.mock import MagicMock, patch
 
-import ray.cluster_utils
+from ray.cluster_utils import Cluster, cluster_not_supported
 from ray._private.test_utils import client_test_enabled
 from ray.tests.client_test_utils import create_remote_signal_actor
 from ray.exceptions import GetTimeoutError
@@ -324,10 +324,11 @@ def test_call_chain(ray_start_cluster):
     assert ray.get(x) == 100
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 @pytest.mark.skipif(client_test_enabled(), reason="init issue")
 def test_system_config_when_connecting(ray_start_cluster):
     config = {"object_timeout_milliseconds": 200}
-    cluster = ray.cluster_utils.Cluster()
+    cluster = Cluster()
     cluster.add_node(
         _system_config=config, object_store_memory=100 * 1024 * 1024)
     cluster.wait_for_nodes()
diff --git a/python/ray/tests/test_cli.py b/python/ray/tests/test_cli.py
index dcbe74729..e59ae8835 100644
--- a/python/ray/tests/test_cli.py
+++ b/python/ray/tests/test_cli.py
@@ -38,6 +38,7 @@ from testfixtures.popen import MockPopen, PopenBehaviour
 
 import ray
 import ray.autoscaler._private.aws.config as aws_config
+from ray.cluster_utils import Cluster, cluster_not_supported
 import ray.scripts.scripts as scripts
 from ray._private.test_utils import wait_for_condition
 
@@ -494,8 +495,8 @@ def test_ray_status():
     ray.shutdown()
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 def test_ray_status_multinode():
-    from ray.cluster_utils import Cluster
     cluster = Cluster()
     for _ in range(4):
         cluster.add_node(num_cpus=2)
diff --git a/python/ray/tests/test_client_builder.py b/python/ray/tests/test_client_builder.py
index 7649b0a26..d8f2d070d 100644
--- a/python/ray/tests/test_client_builder.py
+++ b/python/ray/tests/test_client_builder.py
@@ -43,7 +43,6 @@ def test_client(address):
         assert builder.address == address.replace("ray://", "")
 
 
-@pytest.mark.skipif(sys.platform == "win32", reason="Flaky on Windows.")
 def test_namespace(ray_start_cluster):
     """
     Most of the "checks" in this test case rely on the fact that
diff --git a/python/ray/tests/test_client_init.py b/python/ray/tests/test_client_init.py
index a474d88eb..de317a2b7 100644
--- a/python/ray/tests/test_client_init.py
+++ b/python/ray/tests/test_client_init.py
@@ -11,6 +11,7 @@ import ray.util.client.server.server as ray_client_server
 import ray.core.generated.ray_client_pb2 as ray_client_pb2
 
 from ray.util.client import _ClientContext, CURRENT_PROTOCOL_VERSION
+from ray.cluster_utils import cluster_not_supported
 
 import ray
 
@@ -40,6 +41,7 @@ class C:
         return self.val
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 @pytest.fixture
 def init_and_serve_lazy():
     cluster = ray.cluster_utils.Cluster()
diff --git a/python/ray/tests/test_component_failures_2.py b/python/ray/tests/test_component_failures_2.py
index e0bebf7bd..397c2264e 100644
--- a/python/ray/tests/test_component_failures_2.py
+++ b/python/ray/tests/test_component_failures_2.py
@@ -7,7 +7,7 @@ import pytest
 
 import ray
 import ray.ray_constants as ray_constants
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 from ray._private.test_utils import (
     RayTestTimeoutException,
     get_other_nodes,
@@ -17,6 +17,7 @@ from ray._private.test_utils import (
 SIGKILL = signal.SIGKILL if sys.platform != "win32" else signal.SIGTERM
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 @pytest.fixture(params=[(1, 4), (4, 4)])
 def ray_start_workers_separate_multinode(request):
     num_nodes = request.param[0]
diff --git a/python/ray/tests/test_failure_2.py b/python/ray/tests/test_failure_2.py
index e726668a3..2b1abe7d9 100644
--- a/python/ray/tests/test_failure_2.py
+++ b/python/ray/tests/test_failure_2.py
@@ -14,7 +14,7 @@ from ray.autoscaler._private.util import DEBUG_AUTOSCALING_ERROR
 import ray._private.utils
 from ray.util.placement_group import placement_group
 import ray.ray_constants as ray_constants
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 from ray._private.test_utils import (init_error_pubsub, get_error_message,
                                      get_log_batch, Semaphore,
                                      wait_for_condition)
@@ -377,6 +377,7 @@ def test_serialized_id(ray_start_cluster):
     ray.get(get.remote([obj], True))
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 @pytest.mark.parametrize("use_actors,node_failure",
                          [(False, False), (False, True), (True, False),
                           (True, True)])
diff --git a/python/ray/tests/test_failure_4.py b/python/ray/tests/test_failure_4.py
index 84b5dc058..12ba0db1e 100644
--- a/python/ray/tests/test_failure_4.py
+++ b/python/ray/tests/test_failure_4.py
@@ -8,7 +8,7 @@ import psutil
 
 import ray.ray_constants as ray_constants
 
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 from ray import NodeID
 from ray.core.generated import node_manager_pb2
 from ray.core.generated import node_manager_pb2_grpc
@@ -94,6 +94,7 @@ def test_retry_application_level_error(ray_start_regular):
         ray.get(r3)
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 def test_connect_with_disconnected_node(shutdown_only):
     config = {
         "num_heartbeats_timeout": 50,
diff --git a/python/ray/tests/test_global_gc.py b/python/ray/tests/test_global_gc.py
index 922dad744..d3cc4e036 100644
--- a/python/ray/tests/test_global_gc.py
+++ b/python/ray/tests/test_global_gc.py
@@ -58,6 +58,8 @@ def test_auto_local_gc(shutdown_only):
         gc.enable()
 
 
+@pytest.mark.xfail(
+    ray.cluster_utils.cluster_not_supported, reason="cluster not supported")
 def test_global_gc(shutdown_only):
     cluster = ray.cluster_utils.Cluster()
     cluster.add_node(
@@ -108,6 +110,8 @@ def test_global_gc(shutdown_only):
         gc.enable()
 
 
+@pytest.mark.xfail(
+    ray.cluster_utils.cluster_not_supported, reason="cluster not supported")
 def test_global_gc_when_full(shutdown_only):
     cluster = ray.cluster_utils.Cluster()
     for _ in range(2):
diff --git a/python/ray/tests/test_memstat.py b/python/ray/tests/test_memstat.py
index 70a9655cf..0f1733479 100644
--- a/python/ray/tests/test_memstat.py
+++ b/python/ray/tests/test_memstat.py
@@ -4,7 +4,7 @@ import time
 
 import pytest
 import ray
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 from ray.internal.internal_api import memory_summary
 
 # RayConfig to enable recording call sites during ObjectRej creations.
@@ -233,6 +233,7 @@ def test_pinned_object_call_site(ray_start_regular):
     assert num_objects(info) == 0, info
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 def test_multi_node_stats(shutdown_only):
     # NOTE(mwtian): using env var only enables the feature on workers, while
     # using head_node_args={"_system_config": ray_config} only enables the
diff --git a/python/ray/tests/test_multinode_failures.py b/python/ray/tests/test_multinode_failures.py
index eb95efd03..61627c99c 100644
--- a/python/ray/tests/test_multinode_failures.py
+++ b/python/ray/tests/test_multinode_failures.py
@@ -7,12 +7,13 @@ import pytest
 
 import ray
 import ray.ray_constants as ray_constants
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 from ray._private.test_utils import RayTestTimeoutException, get_other_nodes
 
 SIGKILL = signal.SIGKILL if sys.platform != "win32" else signal.SIGTERM
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 @pytest.fixture(params=[(1, 4), (4, 4)])
 def ray_start_workers_separate_multinode(request):
     num_nodes = request.param[0]
diff --git a/python/ray/tests/test_object_manager.py b/python/ray/tests/test_object_manager.py
index e44bf22e8..81c72cecd 100644
--- a/python/ray/tests/test_object_manager.py
+++ b/python/ray/tests/test_object_manager.py
@@ -6,7 +6,7 @@ import time
 import warnings
 
 import ray
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 from ray.exceptions import GetTimeoutError
 
 if (multiprocessing.cpu_count() < 40
@@ -296,6 +296,7 @@ def test_pull_request_retry(shutdown_only):
     ray.get(driver.remote())
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 def test_pull_bundles_admission_control(shutdown_only):
     cluster = Cluster()
     object_size = int(6e6)
@@ -329,6 +330,7 @@ def test_pull_bundles_admission_control(shutdown_only):
     ray.get(tasks)
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 def test_pull_bundles_pinning(shutdown_only):
     cluster = Cluster()
     object_size = int(50e6)
@@ -353,6 +355,7 @@ def test_pull_bundles_pinning(shutdown_only):
     ray.get(foo.remote(*task_args))
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 def test_pull_bundles_admission_control_dynamic(shutdown_only):
     # This test is the same as test_pull_bundles_admission_control, except that
     # the object store's capacity starts off higher and is later consumed
@@ -399,6 +402,7 @@ def test_pull_bundles_admission_control_dynamic(shutdown_only):
     del allocated
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 def test_max_pinned_args_memory(shutdown_only):
     cluster = Cluster()
     cluster.add_node(
@@ -431,6 +435,7 @@ def test_max_pinned_args_memory(shutdown_only):
     ray.get(large_arg.remote(ref))
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 def test_ray_get_task_args_deadlock(shutdown_only):
     cluster = Cluster()
     object_size = int(6e6)
diff --git a/python/ray/tests/test_object_spilling.py b/python/ray/tests/test_object_spilling.py
index ecde312ad..3763a065e 100644
--- a/python/ray/tests/test_object_spilling.py
+++ b/python/ray/tests/test_object_spilling.py
@@ -15,7 +15,7 @@ from ray.tests.conftest import (file_system_object_spilling_config,
 from ray.external_storage import (create_url_with_offset,
                                   parse_url_with_offset)
 from ray._private.test_utils import wait_for_condition
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 from ray.internal.internal_api import memory_summary
 
 
@@ -601,8 +601,7 @@ def test_pull_spilled_object_failure(object_spilling_config,
     assert hash_value == hash_value1
 
 
-@pytest.mark.skipif(
-    platform.system() == "Windows", reason="Failing on Windows.")
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 def test_spill_dir_cleanup_on_raylet_start(object_spilling_config):
     object_spilling_config, temp_folder = object_spilling_config
     cluster = Cluster()
diff --git a/python/ray/tests/test_ray_debugger.py b/python/ray/tests/test_ray_debugger.py
index 933276b7b..3781c965c 100644
--- a/python/ray/tests/test_ray_debugger.py
+++ b/python/ray/tests/test_ray_debugger.py
@@ -9,7 +9,7 @@ import pexpect
 import pytest
 
 import ray
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 from ray import ray_constants
 from ray._private.test_utils import run_string_as_driver, wait_for_condition
 from ray._private import services
@@ -241,8 +241,7 @@ def test_ray_debugger_public(shutdown_only, call_ray_stop_only,
     ray.get(result)
 
 
-@pytest.mark.skipif(
-    platform.system() == "Windows", reason="Failing on Windows.")
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 @pytest.mark.parametrize("ray_debugger_external", [False, True])
 def test_ray_debugger_public_multi_node(shutdown_only, ray_debugger_external):
     c = Cluster(
diff --git a/python/ray/tests/test_scheduling.py b/python/ray/tests/test_scheduling.py
index 8a5ac92dd..8f92fbb71 100644
--- a/python/ray/tests/test_scheduling.py
+++ b/python/ray/tests/test_scheduling.py
@@ -475,6 +475,8 @@ def test_pull_manager_at_capacity_reports(ray_start_cluster):
     wait_for_condition(lambda: not fetches_queued())
 
 
+@pytest.mark.xfail(
+    ray.cluster_utils.cluster_not_supported, reason="cluster not supported")
 def build_cluster(num_cpu_nodes, num_gpu_nodes):
     cluster = ray.cluster_utils.Cluster()
     gpu_ids = [
diff --git a/python/ray/tests/test_stress.py b/python/ray/tests/test_stress.py
index 99ed18671..a997f9f43 100644
--- a/python/ray/tests/test_stress.py
+++ b/python/ray/tests/test_stress.py
@@ -3,9 +3,10 @@ import pytest
 import time
 
 import ray
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 @pytest.fixture(params=[(1, 4), (4, 4)])
 def ray_start_combination(request):
     num_nodes = request.param[0]
diff --git a/python/ray/tests/test_stress_failure.py b/python/ray/tests/test_stress_failure.py
index 4b4506313..6b156a294 100644
--- a/python/ray/tests/test_stress_failure.py
+++ b/python/ray/tests/test_stress_failure.py
@@ -4,11 +4,12 @@ import sys
 import time
 
 import ray
-from ray.cluster_utils import Cluster
+from ray.cluster_utils import Cluster, cluster_not_supported
 import ray.ray_constants as ray_constants
 from ray._private.test_utils import get_error_message
 
 
+@pytest.mark.xfail(cluster_not_supported, reason="cluster not supported")
 @pytest.fixture(params=[1, 4])
 def ray_start_reconstruction(request):
     num_nodes = request.param