diff --git a/.github/workflows/install-testing.yml b/.github/workflows/install-testing.yml
index 6fa051bf8c289..b9e8612e4c3b1 100644
--- a/.github/workflows/install-testing.yml
+++ b/.github/workflows/install-testing.yml
@@ -1,3 +1,6 @@
+# Confirms that installing WordPress using WP-CLI works successfully.
+#
+# This workflow is not meant to test wordpress-develop checkouts, but rather tagged versions officially available on WordPress.org.
 name: Installation Tests
 
 on:
@@ -11,18 +14,20 @@ on:
     # Always test the workflow when changes are suggested.
     paths:
       - '.github/workflows/install-testing.yml'
+  schedule:
+    - cron: '0 0 * * 1'
   workflow_dispatch:
     inputs:
       wp-version:
         description: 'The version to test installing. Accepts major and minor versions, "latest", or "nightly". Major releases must not end with ".0".'
         type: string
-        default: 'latest'
+        default: 'nightly'
 
 # Cancels all previous workflow runs for pull requests that have not completed.
 concurrency:
   # The concurrency group contains the workflow name and the branch name for pull requests
   # or the commit hash for any other events.
-  group: ${{ github.workflow }}-${{ github.event_name == 'pull_request' && github.head_ref || github.sha }}
+  group: ${{ github.workflow }}-${{ inputs.wp-version || github.event_name == 'pull_request' && github.head_ref || github.sha }}
   cancel-in-progress: true
 
 # Disable permissions for all available scopes by default.
@@ -30,6 +35,60 @@ concurrency:
 permissions: {}
 
 jobs:
+  # Determines the appropriate values for PHP and database versions based on the WordPress version being tested.
+  #
+  # Performs the following steps:
+  # - Checks out the repository.
+  # - Fetches the versions of PHP to test.
+  # - Fetches the versions of MySQL to test.
+  build-matrix:
+    name: Determine PHP Versions to test
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    outputs:
+      major-wp-version: ${{ steps.major-wp-version.outputs.version }}
+      php-versions: ${{ steps.php-versions.outputs.versions }}
+      mysql-versions: ${{ steps.mysql-versions.outputs.versions }}
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+        with:
+          show-progress: ${{ runner.debug == '1' && 'true' || 'false' }}
+
+      - name: Determine the major WordPress version
+        id: major-wp-version
+        run: |
+          if [ "${{ inputs.wp-version }}" ] && [ "${{ inputs.wp-version }}" != "nightly" ] && [ "${{ inputs.wp-version }}" != "latest" ]; then
+            echo "version=$(echo "${{ inputs.wp-version }}" | tr '.' '-' | cut -d '-' -f1-2)" >> $GITHUB_OUTPUT
+          elif [ "${{ inputs.wp-version }}" ]; then
+            echo "version=$(echo "${{ inputs.wp-version }}")" >> $GITHUB_OUTPUT
+          else
+            echo "version=nightly" >> $GITHUB_OUTPUT
+          fi
+
+      # Look up the major version's specific PHP support policy when a version is provided.
+      # Otherwise, use the current PHP support policy.
+      - name: Get supported PHP versions
+        id: php-versions
+        run: |
+          if [ "${{ steps.major-wp-version.outputs.version }}" != "latest" ] && [ "${{ steps.major-wp-version.outputs.version }}" != "nightly" ]; then
+            echo "versions=$(jq -r '.["${{ steps.major-wp-version.outputs.version }}"] | @json' .version-support-php.json)" >> $GITHUB_OUTPUT
+          else
+            echo "versions=$(jq -r '.[ (keys[-1]) ] | @json' .version-support-php.json)" >> $GITHUB_OUTPUT
+          fi
+
+      # Look up the major version's specific MySQL support policy when a version is provided.
+      # Otherwise, use the current MySQL support policy.
+      - name: Get supported MySQL versions
+        id: mysql-versions
+        run: |
+          if [ "${{ steps.major-wp-version.outputs.version }}" != "latest" ] && [ "${{ steps.major-wp-version.outputs.version }}" != "nightly" ]; then
+            echo "versions=$(jq -r '.["${{ steps.major-wp-version.outputs.version }}"] | @json' .version-support-mysql.json)" >> $GITHUB_OUTPUT
+          else
+            echo "versions=$(jq -r '.[ (keys[-1]) ] | @json' .version-support-mysql.json)" >> $GITHUB_OUTPUT
+          fi
+
   # Test the WordPress installation process through WP-CLI.
   #
   # Performs the following steps:
@@ -39,26 +98,44 @@ jobs:
   # - Creates a `wp-config.php` file.
   # - Installs WordPress.
   install-tests-mysql:
-    name: WP ${{ inputs.wp-version || 'latest' }} / PHP ${{ matrix.php }} / ${{ 'mariadb' == matrix.db-type && 'MariaDB' || 'MySQL' }} ${{ matrix.db-version }}${{ matrix.multisite && ' multisite' || '' }}
+    name: WP ${{ inputs.wp-version || 'nightly' }} / PHP ${{ matrix.php }} / ${{ 'mariadb' == matrix.db-type && 'MariaDB' || 'MySQL' }} ${{ matrix.db-version }}${{ matrix.multisite && ' multisite' || '' }}
     permissions:
       contents: read
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     timeout-minutes: 10
+    needs: [ build-matrix ]
     strategy:
       fail-fast: false
       matrix:
         os: [ ubuntu-latest ]
-        php: [ '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3' ]
+        php: ${{ fromJSON( needs.build-matrix.outputs.php-versions ) }}
         db-type: [ 'mysql' ]
-        db-version: [ '5.7', '8.0' ]
+        db-version: ${{ fromJSON( needs.build-matrix.outputs.mysql-versions ) }}
         multisite: [ false, true ]
+        memcached: [ false ]
+
+        # Exclude some PHP and MySQL versions that cannot currently be tested with Docker containers.
+        exclude:
+          - php: '5.2'
+          - php: '5.3'
+          - db-version: '5.0'
+          - db-version: '5.1'
+          - db-version: '5.5'
 
     services:
       database:
         image: ${{ matrix.db-type }}:${{ matrix.db-version }}
         ports:
           - 3306
-        options: --health-cmd="mysqladmin ping" --health-interval=30s --health-timeout=10s --health-retries=5 -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=test_db --entrypoint sh ${{ matrix.db-type }}:${{ matrix.db-version }} -c "exec docker-entrypoint.sh mysqld --default-authentication-plugin=mysql_native_password"
+        options: >-
+          --health-cmd="mysqladmin ping"
+          --health-interval=30s
+          --health-timeout=10s
+          --health-retries=5
+          -e MYSQL_ROOT_PASSWORD=root
+          -e MYSQL_DATABASE=test_db
+          --entrypoint sh ${{ matrix.db-type }}:${{ matrix.db-version }}
+          -c "exec docker-entrypoint.sh mysqld${{ matrix.db-version != '5.5' && ' --default-authentication-plugin=mysql_native_password"' || '' }}
 
     steps:
       - name: Set up PHP ${{ matrix.php }}
@@ -66,14 +143,14 @@ jobs:
         with:
           php-version: '${{ matrix.php }}'
           coverage: none
-          tools: wp-cli
+          tools: wp-cli${{ contains( fromJSON('["5.4", "5.5"]'), matrix.php ) && ':2.4.0' || '' }}
 
       - name: Start the database server
         run: |
           sudo systemctl start ${{ matrix.db-type }}
 
       - name: Download WordPress
-        run: wp core download ${{ inputs.wp-version && 'latest' != inputs.wp-version && format( '--version={0}', inputs.wp-version ) || '' }}
+        run: wp core download ${{ inputs.wp-version && format( '--version={0}', inputs.wp-version ) || '--version=nightly' }}
 
       - name: Create wp-config.php file
         run: wp config create --dbname=test_db --dbuser=root --dbpass=root --dbhost=127.0.0.1:${{ job.services.database.ports['3306'] }}
diff --git a/.version-support-mysql.json b/.version-support-mysql.json
new file mode 100644
index 0000000000000..7cb068ba5c0c1
--- /dev/null
+++ b/.version-support-mysql.json
@@ -0,0 +1,188 @@
+{
+	"6-5": [
+		"8.2",
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5"
+	],
+	"6-4": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"6-3": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"6-2": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"6-1": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"6-0": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"5-9": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"5-8": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"5-7": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"5-6": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"5-5": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"5-4": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"5-3": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"5-2": [
+		"8.0",
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"5-1": [
+		"5.7",
+		"5.6",
+		"5.5"
+	],
+	"5-0": [
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"4-9": [
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"4-8": [
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"4-7": [
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"4-6": [
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"4-5": [
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"4-4": [
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"4-3": [
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"4-2": [
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	],
+	"4-1": [
+		"5.7",
+		"5.6",
+		"5.5",
+		"5.1",
+		"5.0"
+	]
+}
diff --git a/.version-support-php.json b/.version-support-php.json
new file mode 100644
index 0000000000000..48bff25d2fe0d
--- /dev/null
+++ b/.version-support-php.json
@@ -0,0 +1,208 @@
+{
+	"6-3": [
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4",
+		"8.0",
+		"8.1",
+		"8.2",
+		"8.3"
+	],
+	"6-2": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4",
+		"8.0",
+		"8.1",
+		"8.2"
+	],
+	"6-1": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4",
+		"8.0",
+		"8.1",
+		"8.2"
+	],
+	"6-0": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4",
+		"8.0",
+		"8.1"
+	],
+	"5-9": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4",
+		"8.0",
+		"8.1"
+	],
+	"5-8": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4",
+		"8.0"
+	],
+	"5-7": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4",
+		"8.0"
+	],
+	"5-6": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4",
+		"8.0"
+	],
+	"5-5": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4"
+	],
+	"5-4": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4"
+	],
+	"5-3": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3",
+		"7.4"
+	],
+	"5-2": [
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3"
+	],
+	"5-1": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3"
+	],
+	"5-0": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2",
+		"7.3"
+	],
+	"4-9": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6",
+		"7.0",
+		"7.1",
+		"7.2"
+	],
+	"4-8": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6",
+		"7.0",
+		"7.1"
+	],
+	"4-7": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6",
+		"7.0",
+		"7.1"
+	],
+	"4-6": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6",
+		"7.0"
+	],
+	"4-5": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6",
+		"7.0"
+	],
+	"4-4": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6",
+		"7.0"
+	],
+	"4-3": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6"
+	],
+	"4-2": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6"
+	],
+	"4-1": [
+		"5.2",
+		"5.3",
+		"5.4",
+		"5.5",
+		"5.6"
+	]
+}