diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 8d8ab246..a20a689f 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -14,6 +14,12 @@ jobs:
           - ubuntu-latest
         python-version:
           ["3.10", "3.11", "3.12", "3.13", "3.14", "3.14t", pypy3.11]
+        include:
+          # Windows: Test lowest and highest supported Python versions
+          - os: windows-latest
+            python-version: "3.10"
+          - os: windows-latest
+            python-version: "3.14"
 
     steps:
       - uses: actions/checkout@v6
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 7cc4533d..ebc4fdd9 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -1,15 +1,18 @@
 import os
 import subprocess
+import sys
 from pathlib import Path
 from typing import Optional, Sequence
 
 import pytest
-import sh
 
 import dotenv
 from dotenv.cli import cli as dotenv_cli
 from dotenv.version import __version__
 
+if sys.platform != "win32":
+    import sh
+
 
 def invoke_sub(args: Sequence[str]) -> subprocess.CompletedProcess:
     """
@@ -189,6 +192,7 @@ def test_set_no_file(cli):
     assert "Missing argument" in result.output
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="sh module doesn't support Windows")
 def test_get_default_path(tmp_path):
     with sh.pushd(tmp_path):
         (tmp_path / ".env").write_text("a=b")
@@ -198,6 +202,7 @@ def test_get_default_path(tmp_path):
         assert result == "b\n"
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="sh module doesn't support Windows")
 def test_run(tmp_path):
     with sh.pushd(tmp_path):
         (tmp_path / ".env").write_text("a=b")
@@ -207,6 +212,7 @@ def test_run(tmp_path):
         assert result == "b\n"
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="sh module doesn't support Windows")
 def test_run_with_existing_variable(tmp_path):
     with sh.pushd(tmp_path):
         (tmp_path / ".env").write_text("a=b")
@@ -218,6 +224,7 @@ def test_run_with_existing_variable(tmp_path):
         assert result == "b\n"
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="sh module doesn't support Windows")
 def test_run_with_existing_variable_not_overridden(tmp_path):
     with sh.pushd(tmp_path):
         (tmp_path / ".env").write_text("a=b")
@@ -229,6 +236,7 @@ def test_run_with_existing_variable_not_overridden(tmp_path):
         assert result == "c\n"
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="sh module doesn't support Windows")
 def test_run_with_none_value(tmp_path):
     with sh.pushd(tmp_path):
         (tmp_path / ".env").write_text("a=b\nc")
@@ -238,6 +246,7 @@ def test_run_with_none_value(tmp_path):
         assert result == "b\n"
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="sh module doesn't support Windows")
 def test_run_with_other_env(dotenv_path):
     dotenv_path.write_text("a=b")
 
diff --git a/tests/test_fifo_dotenv.py b/tests/test_fifo_dotenv.py
index 4961adce..2aa31779 100644
--- a/tests/test_fifo_dotenv.py
+++ b/tests/test_fifo_dotenv.py
@@ -7,9 +7,7 @@
 
 from dotenv import load_dotenv
 
-pytestmark = pytest.mark.skipif(
-    sys.platform.startswith("win"), reason="FIFOs are Unix-only"
-)
+pytestmark = pytest.mark.skipif(sys.platform == "win32", reason="FIFOs are Unix-only")
 
 
 def test_load_dotenv_from_fifo(tmp_path: pathlib.Path, monkeypatch):
diff --git a/tests/test_ipython.py b/tests/test_ipython.py
index f01b3ad7..6eda086b 100644
--- a/tests/test_ipython.py
+++ b/tests/test_ipython.py
@@ -1,4 +1,5 @@
 import os
+import sys
 from unittest import mock
 
 import pytest
@@ -6,6 +7,9 @@
 pytest.importorskip("IPython")
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @mock.patch.dict(os.environ, {}, clear=True)
 def test_ipython_existing_variable_no_override(tmp_path):
     from IPython.terminal.embed import InteractiveShellEmbed
@@ -22,6 +26,9 @@ def test_ipython_existing_variable_no_override(tmp_path):
     assert os.environ == {"a": "c"}
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @mock.patch.dict(os.environ, {}, clear=True)
 def test_ipython_existing_variable_override(tmp_path):
     from IPython.terminal.embed import InteractiveShellEmbed
@@ -38,6 +45,9 @@ def test_ipython_existing_variable_override(tmp_path):
     assert os.environ == {"a": "b"}
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @mock.patch.dict(os.environ, {}, clear=True)
 def test_ipython_new_variable(tmp_path):
     from IPython.terminal.embed import InteractiveShellEmbed
diff --git a/tests/test_main.py b/tests/test_main.py
index 76c1f70e..761bdad3 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -1,15 +1,18 @@
 import io
 import logging
 import os
+import stat
 import sys
 import textwrap
 from unittest import mock
 
 import pytest
-import sh
 
 import dotenv
 
+if sys.platform != "win32":
+    import sh
+
 
 def test_set_key_no_file(tmp_path):
     nx_path = tmp_path / "nx"
@@ -62,15 +65,25 @@ def test_set_key_encoding(dotenv_path):
 
 
 @pytest.mark.skipif(
-    os.geteuid() == 0, reason="Root user can access files even with 000 permissions."
+    sys.platform != "win32" and os.geteuid() == 0,
+    reason="Root user can access files even with 000 permissions.",
 )
 def test_set_key_permission_error(dotenv_path):
-    dotenv_path.chmod(0o000)
+    if sys.platform == "win32":
+        # On Windows, make file read-only
+        dotenv_path.chmod(stat.S_IREAD)
+    else:
+        # On Unix, remove all permissions
+        dotenv_path.chmod(0o000)
 
     with pytest.raises(PermissionError):
         dotenv.set_key(dotenv_path, "a", "b")
 
-    dotenv_path.chmod(0o600)
+    # Restore permissions
+    if sys.platform == "win32":
+        dotenv_path.chmod(stat.S_IWRITE | stat.S_IREAD)
+    else:
+        dotenv_path.chmod(0o600)
     assert dotenv_path.read_text() == ""
 
 
@@ -170,16 +183,6 @@ def test_unset_encoding(dotenv_path):
     assert dotenv_path.read_text(encoding=encoding) == ""
 
 
-@pytest.mark.skipif(
-    os.geteuid() == 0, reason="Root user can access files even with 000 permissions."
-)
-def test_set_key_unauthorized_file(dotenv_path):
-    dotenv_path.chmod(0o000)
-
-    with pytest.raises(PermissionError):
-        dotenv.set_key(dotenv_path, "a", "x")
-
-
 def test_unset_non_existent_file(tmp_path):
     nx_path = tmp_path / "nx"
     logger = logging.getLogger("dotenv.main")
@@ -241,6 +244,9 @@ def test_find_dotenv_found(tmp_path):
     assert result == str(dotenv_path)
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @mock.patch.dict(os.environ, {}, clear=True)
 def test_load_dotenv_existing_file(dotenv_path):
     dotenv_path.write_text("a=b")
@@ -312,6 +318,9 @@ def test_load_dotenv_disabled_notification(dotenv_path, flag_value):
         )
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @pytest.mark.parametrize(
     "flag_value",
     [
@@ -395,6 +404,9 @@ def test_load_dotenv_no_file_verbose():
     )
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @mock.patch.dict(os.environ, {"a": "c"}, clear=True)
 def test_load_dotenv_existing_variable_no_override(dotenv_path):
     dotenv_path.write_text("a=b")
@@ -405,6 +417,9 @@ def test_load_dotenv_existing_variable_no_override(dotenv_path):
     assert os.environ == {"a": "c"}
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @mock.patch.dict(os.environ, {"a": "c"}, clear=True)
 def test_load_dotenv_existing_variable_override(dotenv_path):
     dotenv_path.write_text("a=b")
@@ -415,6 +430,9 @@ def test_load_dotenv_existing_variable_override(dotenv_path):
     assert os.environ == {"a": "b"}
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @mock.patch.dict(os.environ, {"a": "c"}, clear=True)
 def test_load_dotenv_redefine_var_used_in_file_no_override(dotenv_path):
     dotenv_path.write_text('a=b\nd="${a}"')
@@ -425,6 +443,9 @@ def test_load_dotenv_redefine_var_used_in_file_no_override(dotenv_path):
     assert os.environ == {"a": "c", "d": "c"}
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @mock.patch.dict(os.environ, {"a": "c"}, clear=True)
 def test_load_dotenv_redefine_var_used_in_file_with_override(dotenv_path):
     dotenv_path.write_text('a=b\nd="${a}"')
@@ -435,6 +456,9 @@ def test_load_dotenv_redefine_var_used_in_file_with_override(dotenv_path):
     assert os.environ == {"a": "b", "d": "b"}
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @mock.patch.dict(os.environ, {}, clear=True)
 def test_load_dotenv_string_io_utf_8():
     stream = io.StringIO("a=à")
@@ -445,6 +469,9 @@ def test_load_dotenv_string_io_utf_8():
     assert os.environ == {"a": "à"}
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @mock.patch.dict(os.environ, {}, clear=True)
 def test_load_dotenv_file_stream(dotenv_path):
     dotenv_path.write_text("a=b")
@@ -456,6 +483,7 @@ def test_load_dotenv_file_stream(dotenv_path):
     assert os.environ == {"a": "b"}
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="sh module doesn't support Windows")
 def test_load_dotenv_in_current_dir(tmp_path):
     dotenv_path = tmp_path / ".env"
     dotenv_path.write_bytes(b"a=b")
@@ -484,6 +512,9 @@ def test_dotenv_values_file(dotenv_path):
     assert result == {"a": "b"}
 
 
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="This test assumes case-sensitive variable names"
+)
 @pytest.mark.parametrize(
     "env,string,interpolate,expected",
     [
diff --git a/tests/test_zip_imports.py b/tests/test_zip_imports.py
index 5c0fb88d..0b57a1c5 100644
--- a/tests/test_zip_imports.py
+++ b/tests/test_zip_imports.py
@@ -5,7 +5,10 @@
 from unittest import mock
 from zipfile import ZipFile
 
-import sh
+import pytest
+
+if sys.platform != "win32":
+    import sh
 
 
 def walk_to_root(path: str):
@@ -62,6 +65,7 @@ def test_load_dotenv_gracefully_handles_zip_imports_when_no_env_file(tmp_path):
     import child1.child2.test  # noqa
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="sh module doesn't support Windows")
 def test_load_dotenv_outside_zip_file_when_called_in_zipfile(tmp_path):
     zip_file_path = setup_zipfile(
         tmp_path,