diff --git a/server.py b/server.py
index cbb9f25..347d9e4 100644
--- a/server.py
+++ b/server.py
@@ -2153,6 +2153,20 @@ class MetadataDB:
             # '2005' rather than alphabetic.
             "year": "(year = '') ASC, CAST(year AS INTEGER) ASC",
             "year-desc": "(year = '') ASC, CAST(year AS INTEGER) DESC",
+            # Mastery = best accuracy across a song's arrangements, from the
+            # separate song_stats table (so via a correlated subquery — this sort
+            # drops to OFFSET paging, like tuning/year). Unscored ("not started")
+            # songs push to the BOTTOM in both directions (the IS NULL term);
+            # ascending is "needs practice first" (weakest measured first),
+            # descending is "most mastered first".
+            "mastery": (
+                "((SELECT MAX(best_accuracy) FROM song_stats s WHERE s.filename = songs.filename) IS NULL) ASC, "
+                "(SELECT MAX(best_accuracy) FROM song_stats s WHERE s.filename = songs.filename) ASC"
+            ),
+            "mastery-desc": (
+                "((SELECT MAX(best_accuracy) FROM song_stats s WHERE s.filename = songs.filename) IS NULL) ASC, "
+                "(SELECT MAX(best_accuracy) FROM song_stats s WHERE s.filename = songs.filename) DESC"
+            ),
         }
         order = sort_map.get(sort, "artist COLLATE NOCASE")
         # Legacy `dir=desc` toggle: only safe to append on simple sort
diff --git a/static/v3/songs.js b/static/v3/songs.js
index 5b64135..8e7b182 100644
--- a/static/v3/songs.js
+++ b/static/v3/songs.js
@@ -35,6 +35,9 @@
         ['title', 'Title A–Z'], ['title-desc', 'Title Z–A'],
         ['recent', 'Recently Added'], ['year-desc', 'Year (newest)'],
         ['year', 'Year (oldest)'], ['tuning', 'Tuning'],
+        // Mastery = best accuracy across arrangements (song_stats); unscored songs
+        // sort last either way. Ascending surfaces what needs work; never default.
+        ['mastery', 'Needs practice first'], ['mastery-desc', 'Most mastered first'],
     ];
     const FORMATS = [['', 'All formats'], ['sloppak', 'Feedpak'], ['loose', 'Folder']];
     const ARRANGEMENTS = ['Lead', 'Rhythm', 'Bass', 'Combo', 'Vocals'];