diff --git a/.gitignore b/.gitignore
index 64c6627..5fb8656 100644
--- a/.gitignore
+++ b/.gitignore
@@ -30,5 +30,11 @@ yarn-error.log
 phpstan.neon
 ###< phpstan/phpstan ###
 .phpunit.cache
+
+###> symfony/asset-mapper ###
+/public/assets/
+/assets/vendor/
+###< symfony/asset-mapper ###
+
 .twig-cs-fixer.cache
 .playwright-mcp
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7ee3096..1d3c760 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- [#81](https://github.com/itk-dev/devops_itksites/pull/81) 5564: Asset Mapper migration
+  - Add Symfony Asset Mapper bundle and importmap
+
 ## [1.11.0] - 2026-05-19
 
 - [#78](https://github.com/itk-dev/devops_itksites/pull/78)
diff --git a/assets/app.js b/assets/app.js
new file mode 100644
index 0000000..e2824a5
--- /dev/null
+++ b/assets/app.js
@@ -0,0 +1,9 @@
+/*
+ * Welcome to your app's main JavaScript file!
+ *
+ * This file will be included onto the page via the importmap() Twig function,
+ * which should already be in your base.html.twig.
+ */
+import "./styles/app.css";
+
+console.log("This log comes from assets/app.js - welcome to AssetMapper! 🎉");
diff --git a/assets/styles/app.css b/assets/styles/app.css
new file mode 100644
index 0000000..8218dc7
--- /dev/null
+++ b/assets/styles/app.css
@@ -0,0 +1,28 @@
+:root {
+    --body-max-width: 100%;
+    --sidebar-bg: #fff;
+    /* make the base font size smaller */
+    --button-primary-bg: rgb(0, 123, 166);
+    --pagination-active-bg: rgb(0, 123, 166);
+    --link-color: rgb(0, 123, 166);
+    --sidebar-menu-active-item-color: rgb(0, 123, 166);
+    --badge-boolean-true-bg: rgb(0, 123, 166);
+    --badge-boolean-false-bg: rgb(228, 73, 48);
+    --badge-boolean-false-color: var(--white);
+    --sidebar-menu-color: rgb(66, 66, 66);
+    --text-color-dark: rgb(66, 66, 66);
+    --bs-danger-rgb: 228, 73, 48;
+}
+
+/* Grouped dropdown group styling for index pages */
+.dropdown-menu {
+    .btn-danger i,
+    .text-danger i {
+        color: var(--button-invisible-danger-color);
+    }
+
+    a.btn-danger:hover,
+    a.text-danger:hover {
+        background: var(--button-invisible-danger-hover-hover-bg);
+    }
+}
diff --git a/composer.json b/composer.json
index 1737658..efe1ca0 100644
--- a/composer.json
+++ b/composer.json
@@ -21,6 +21,7 @@
         "phpstan/phpdoc-parser": "^2.0",
         "symfony/amqp-messenger": "^8.0",
         "symfony/asset": "^8.0",
+        "symfony/asset-mapper": "~8.0.0",
         "symfony/browser-kit": "^8.0",
         "symfony/console": "^8.0",
         "symfony/doctrine-messenger": "^8.0",
@@ -111,7 +112,8 @@
         ],
         "auto-scripts": {
             "cache:clear": "symfony-cmd",
-            "assets:install %PUBLIC_DIR%": "symfony-cmd"
+            "assets:install %PUBLIC_DIR%": "symfony-cmd",
+            "importmap:install": "symfony-cmd"
         },
         "coding-standards-apply": [
             "vendor/bin/php-cs-fixer fix"
diff --git a/composer.lock b/composer.lock
index 9392a9d..277f9e3 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "d3d28912efc62de1dcb6b25446712071",
+    "content-hash": "2a1b30ad222f086b612ec724b183c9eb",
     "packages": [
         {
             "name": "api-platform/core",
@@ -3317,6 +3317,87 @@
             ],
             "time": "2026-03-30T15:14:47+00:00"
         },
+        {
+            "name": "symfony/asset-mapper",
+            "version": "v8.0.11",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/asset-mapper.git",
+                "reference": "b2c33bf6934bfe5b37a6d70d0b0f7011d0ec4a0c"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/asset-mapper/zipball/b2c33bf6934bfe5b37a6d70d0b0f7011d0ec4a0c",
+                "reference": "b2c33bf6934bfe5b37a6d70d0b0f7011d0ec4a0c",
+                "shasum": ""
+            },
+            "require": {
+                "composer/semver": "^3.0",
+                "php": ">=8.4",
+                "symfony/filesystem": "^7.4|^8.0",
+                "symfony/http-client": "^7.4|^8.0"
+            },
+            "require-dev": {
+                "symfony/asset": "^7.4|^8.0",
+                "symfony/browser-kit": "^7.4|^8.0",
+                "symfony/console": "^7.4|^8.0",
+                "symfony/event-dispatcher-contracts": "^3.0",
+                "symfony/finder": "^7.4|^8.0",
+                "symfony/framework-bundle": "^7.4|^8.0",
+                "symfony/http-foundation": "^7.4|^8.0",
+                "symfony/http-kernel": "^7.4|^8.0",
+                "symfony/process": "^7.4|^8.0",
+                "symfony/runtime": "^7.4|^8.0",
+                "symfony/web-link": "^7.4|^8.0"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Component\\AssetMapper\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Maps directories of assets & makes them available in a public directory with versioned filenames.",
+            "homepage": "https://symfony.com",
+            "support": {
+                "source": "https://github.com/symfony/asset-mapper/tree/v8.0.11"
+            },
+            "funding": [
+                {
+                    "url": "https://symfony.com/sponsor",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://github.com/fabpot",
+                    "type": "github"
+                },
+                {
+                    "url": "https://github.com/nicolas-grekas",
+                    "type": "github"
+                },
+                {
+                    "url": "https://tidelift.com/funding/github/packagist/symfony/symfony",
+                    "type": "tidelift"
+                }
+            ],
+            "time": "2026-05-13T12:07:53+00:00"
+        },
         {
             "name": "symfony/browser-kit",
             "version": "v8.0.8",
diff --git a/config/packages/asset_mapper.yaml b/config/packages/asset_mapper.yaml
new file mode 100644
index 0000000..f7653e9
--- /dev/null
+++ b/config/packages/asset_mapper.yaml
@@ -0,0 +1,11 @@
+framework:
+    asset_mapper:
+        # The paths to make available to the asset mapper.
+        paths:
+            - assets/
+        missing_import_mode: strict
+
+when@prod:
+    framework:
+        asset_mapper:
+            missing_import_mode: warn
diff --git a/config/reference.php b/config/reference.php
index a632abf..563c307 100644
--- a/config/reference.php
+++ b/config/reference.php
@@ -280,7 +280,7 @@
  *         }>,
  *     },
  *     asset_mapper?: bool|array{ // Asset Mapper configuration
- *         enabled?: bool|Param, // Default: false
+ *         enabled?: bool|Param, // Default: true
  *         paths?: string|array<string, scalar|Param|null>,
  *         excluded_patterns?: list<scalar|Param|null>,
  *         exclude_dotfiles?: bool|Param, // If true, any files starting with "." will be excluded from the asset mapper. // Default: true
diff --git a/importmap.php b/importmap.php
new file mode 100644
index 0000000..70ebf14
--- /dev/null
+++ b/importmap.php
@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * Returns the importmap for this application.
+ *
+ * - "path" is a path inside the asset mapper system. Use the
+ *     "debug:asset-map" command to see the full list of paths.
+ *
+ * - "entrypoint" (JavaScript only) set to true for any module that will
+ *     be used as an "entrypoint" (and passed to the importmap() Twig function).
+ *
+ * The "importmap:require" command can be used to add new entries to this file.
+ */
+return [
+    'app' => [
+        'path' => './assets/app.js',
+        'entrypoint' => true,
+    ],
+];
diff --git a/psalm.xml b/psalm.xml
deleted file mode 100644
index bedf5ac..0000000
--- a/psalm.xml
+++ /dev/null
@@ -1,27 +0,0 @@
-<?xml version="1.0"?>
-<psalm
-        errorLevel="2"
-        resolveFromConfigFile="true"
-        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-        xmlns="https://getpsalm.org/schema/config"
-        xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
->
-    <projectFiles>
-        <directory name="src"/>
-        <ignoreFiles>
-            <directory name="vendor"/>
-            <file name="src/Kernel.php"/>
-        </ignoreFiles>
-    </projectFiles>
-    <issueHandlers>
-        <UndefinedClass>
-            <errorLevel type="suppress">
-                <referencedClass name="App\Repository\*Repository" />
-            </errorLevel>
-        </UndefinedClass>
-    </issueHandlers>
-    <plugins>
-        <pluginClass class="Weirdan\DoctrinePsalmPlugin\Plugin"/>
-        <pluginClass class="Psalm\SymfonyPsalmPlugin\Plugin"/>
-    </plugins>
-</psalm>
diff --git a/public/css/admin.css b/public/css/admin.css
deleted file mode 100644
index 853c0f8..0000000
--- a/public/css/admin.css
+++ /dev/null
@@ -1,15 +0,0 @@
-:root {
-    --body-max-width: 100%;
-    --sidebar-bg: #fff;
-    /* make the base font size smaller */
-    --button-primary-bg: rgb(0,123,166);
-    --pagination-active-bg: rgb(0,123,166);
-    --link-color: rgb(0,123,166);
-    --sidebar-menu-active-item-color: rgb(0,123,166);
-    --badge-boolean-true-bg: rgb(0,123,166);
-    --badge-boolean-false-bg: rgb(228, 73, 48);
-    --badge-boolean-false-color: var(--white);
-    --sidebar-menu-color: rgb(66,66,66);
-    --text-color-dark: rgb(66,66,66);
-    --bs-danger-rgb: 228, 73, 48;
-}
\ No newline at end of file
diff --git a/symfony.lock b/symfony.lock
index 1033474..4e95b38 100644
--- a/symfony.lock
+++ b/symfony.lock
@@ -307,6 +307,21 @@
     "symfony/asset": {
         "version": "v6.0.3"
     },
+    "symfony/asset-mapper": {
+        "version": "7.3",
+        "recipe": {
+            "repo": "github.com/symfony/recipes",
+            "branch": "main",
+            "version": "6.4",
+            "ref": "5ad1308aa756d58f999ffbe1540d1189f5d7d14a"
+        },
+        "files": [
+            "assets/app.js",
+            "assets/styles/app.css",
+            "config/packages/asset_mapper.yaml",
+            "importmap.php"
+        ]
+    },
     "symfony/browser-kit": {
         "version": "v6.0.3"
     },