diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index d996c02..ae9c7b3 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -25,23 +25,16 @@ on:
 concurrency:
   group: build-${{ github.ref }}
 
-defaults:
-  run:
-    shell: micromamba-shell {0}
-
 jobs:
   date:
     runs-on: ubuntu-latest
     steps:
       - run: echo "date=$(date +%Y-%m-%d)" >> $GITHUB_OUTPUT
         id: date        
-        shell: bash
     outputs:
       date: ${{ steps.date.outputs.date }}
   version:
     runs-on: ubuntu-latest
-    outputs:
-      version: ${{ steps.version.outputs.version }}
     steps:
       - uses: actions/checkout@v4
         with:
@@ -53,16 +46,23 @@ jobs:
         id: version
         with:
           args: --pattern "(?P<base>\d+\.\d+\.\d+)"
+    outputs:
+      version: ${{ steps.version.outputs.version }}
   build:
     needs: [ date, version ]
     strategy:
       fail-fast: false
       matrix:
-        runs-on: [ ubuntu-latest, macos-latest, macos-14 ]
+        runs-on: [ ubuntu-latest, macos-latest, macos-14, windows-latest ]
         python-version: [ '3.9', '3.10', '3.11' ]
     runs-on: ${{ matrix.runs-on }}
     name: build (Python ${{ matrix.python-version }}, ${{ matrix.runs-on }})
+    defaults:
+      run:
+        shell: ${{ matrix.runs-on != 'windows-latest' && 'bash -leo {0}' || 'wsl-bash {0}' }}
     steps:
+      - if: matrix.runs-on == 'windows-latest'
+        uses: Vampire/setup-wsl@v2
       - uses: actions/checkout@v4
       - uses: mamba-org/setup-micromamba@v1
         with:
@@ -75,8 +75,9 @@ jobs:
           cache-downloads-key: downloads-${{ needs.date.outputs.date }}
           cache-environment: true
           cache-environment-key: environment-${{ needs.date.outputs.date }}
-          init-shell: none
-          generate-run-shell: true
+          init-shell: >-
+            ${{ matrix.runs-on != 'windows' && 'bash' || 'wsl-bash' }}
+          generate-run-shell: false
       - run: conda env export --no-build | grep -v "name:" | grep -v "prefix:"
       - run: pytest -n auto tests/test_import.py
       - run: echo "filename=stenv-${{ runner.os }}-${{ runner.arch }}-py${{ matrix.python-version }}-${{ needs.version.outputs.version }}.yaml" >> $GITHUB_OUTPUT
diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index 4788ba0..5953173 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -8,10 +8,6 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
-defaults:
-  run:
-    shell: micromamba-shell {0}
-
 env:
   CRDS_PATH: /tmp/crds_cache
   CRDS_CLIENT_RETRY_COUNT: 3
@@ -27,7 +23,7 @@ jobs:
     strategy:
       matrix:
         package: [ acstools, asdf, calcos, ccdproc, costools, synphot, jwst ]
-        runs-on: [ ubuntu-latest, macos-latest, macos-14 ]
+        runs-on: [ ubuntu-latest, macos-latest, macos-14, windows-latest ]
         python-version: [ '3.9', '3.10', '3.11' ]
         include:
           - package: acstools
@@ -68,7 +64,12 @@ jobs:
       fail-fast: false
     runs-on: ${{ matrix.runs-on }}
     name: ${{ matrix.package }} (Python ${{ matrix.python-version }}, tox ${{ matrix.default_factors }}${{ matrix.args != '' && ' -- ' || '' }}${{ matrix.args }}, ${{ matrix.runs-on }})
+    defaults:
+      run:
+        shell: ${{ matrix.runs-on != 'windows-latest' && 'bash -leo {0}' || 'wsl-bash {0}' }}
     steps:
+      - if: matrix.runs-on == 'windows-latest'
+        uses: Vampire/setup-wsl@v2
       - uses: actions/checkout@v4
         with:
           path: stenv
@@ -119,10 +120,9 @@ jobs:
   unit_tests_via_package:
     needs: [ build ]
     strategy:
-      fail-fast: false
       matrix:
         package: [ reftools, wfpc2tools ]
-        runs-on: [ ubuntu-latest, macos-latest, macos-14 ]
+        runs-on: [ ubuntu-latest, macos-latest, macos-14, windows-latest ]
         python-version: [ '3.9', '3.10', '3.11' ]
         include:
           #- package: pysynphot
@@ -139,9 +139,15 @@ jobs:
             python-version: '3.9'
           - runs-on: macos-14
             python-version: '3.10'
+      fail-fast: false
     runs-on: ${{ matrix.runs-on }}
     name: ${{ matrix.package }} (Python ${{ matrix.python-version }}, ${{ matrix.runs-on }})
+    defaults:
+      run:
+        shell: ${{ matrix.runs-on != 'windows-latest' && 'bash -leo {0}' || 'wsl-bash {0}' }}
     steps:
+      - if: matrix.runs-on == 'windows'
+        uses: Vampire/setup-wsl@v2
       - uses: actions/checkout@v4
       - uses: mamba-org/setup-micromamba@v1
         with:
@@ -177,7 +183,7 @@ jobs:
     strategy:
       matrix:
         package: [ hstcal ]
-        runs-on: [ ubuntu-latest, macos-latest, macos-14 ]
+        runs-on: [ ubuntu-latest, macos-latest, macos-14, windows-latest ]
         python-version: [ '3.9', '3.10', '3.11' ]
         include:
           #- package: drizzlepac
@@ -206,7 +212,12 @@ jobs:
       fail-fast: false
     runs-on: ${{ matrix.runs-on }}
     name: ${{ matrix.package }} (Python ${{ matrix.python-version }}, ${{ matrix.runs-on }})
+    defaults:
+      run:
+        shell: ${{ matrix.runs-on != 'windows-latest' && 'bash -leo {0}' || 'wsl-bash {0}' }}
     steps:
+      - if: matrix.runs-on == 'windows-latest'
+        uses: Vampire/setup-wsl@v2
       - uses: actions/checkout@v4
         with:
           path: stenv
@@ -262,10 +273,9 @@ jobs:
       CRDS_TEST_ROOT: /tmp
       CRDS_TESTING_CACHE: /tmp/crds-cache-test
     strategy:
-      fail-fast: false
       matrix:
         package: [ crds ]
-        runs-on: [ ubuntu-latest, macos-latest, macos-14 ]
+        runs-on: [ ubuntu-latest, macos-latest, macos-14, windows-latest ]
         python-version: [ '3.9', '3.10', '3.11' ]
         include:
           - package: crds
@@ -279,9 +289,15 @@ jobs:
             python-version: '3.9'
           - runs-on: macos-14
             python-version: '3.10'
+      fail-fast: false
     runs-on: ${{ matrix.runs-on }}
     name: ${{ matrix.package }} (Python ${{ matrix.python-version }}, ${{ matrix.runs-on }})
+    defaults:
+      run:
+        shell: ${{ matrix.runs-on != 'windows-latest' && 'bash -leo {0}' || 'wsl-bash {0}' }}
     steps:
+      - if: matrix.runs-on == 'windows-latest'
+        uses: Vampire/setup-wsl@v2
       - uses: actions/checkout@v4
         with:
           path: stenv
@@ -327,7 +343,7 @@ jobs:
     strategy:
       matrix:
         package: [ calcos, drizzlepac ]
-        runs-on: [ ubuntu-latest, macos-latest, macos-14 ]
+        runs-on: [ ubuntu-latest, macos-latest, macos-14, windows-latest ]
         python-version: [ '3.9', '3.10', '3.11' ]
         include:
           - package: calcos
@@ -352,7 +368,12 @@ jobs:
       fail-fast: false
     runs-on: ${{ matrix.runs-on }}
     name: ${{ matrix.package }} (Python ${{ matrix.python-version }}, ${{ matrix.runs-on }})
+    defaults:
+      run:
+        shell: ${{ matrix.runs-on != 'windows-latest' && 'bash -leo {0}' || 'wsl-bash {0}' }}
     steps:
+      - if: matrix.runs-on == 'windows-latest'
+        uses: Vampire/setup-wsl@v2
       - uses: actions/checkout@v4
         with:
           lfs: true