diff --git a/Harmonia.Core/Events/PlaylistUpdateAction.cs b/Harmonia.Core/Events/PlaylistUpdateAction.cs
new file mode 100644
index 0000000..695fd89
--- /dev/null
+++ b/Harmonia.Core/Events/PlaylistUpdateAction.cs
@@ -0,0 +1,21 @@
+namespace Harmonia.Core.Events;
+
+public enum PlaylistUpdateAction
+{
+    /// <summary>
+    /// An item was added to the collection.
+    /// </summary>
+    Add,
+    /// <summary>
+    /// An item was removed from the collection.
+    /// </summary>
+    Remove,
+    /// <summary>
+    /// An item was moved within the collection.
+    /// </summary>
+    Move,
+    /// <summary>
+    /// The contents of the collection changed dramatically.
+    /// </summary>
+    Reset
+}
\ No newline at end of file
diff --git a/Harmonia.Core/Events/PlaylistUpdatedEventArgs.cs b/Harmonia.Core/Events/PlaylistUpdatedEventArgs.cs
new file mode 100644
index 0000000..45e3fdb
--- /dev/null
+++ b/Harmonia.Core/Events/PlaylistUpdatedEventArgs.cs
@@ -0,0 +1,12 @@
+using Harmonia.Core.Models;
+
+namespace Harmonia.Core.Events;
+
+public class PlaylistUpdatedEventArgs : EventArgs
+{
+    public required PlaylistUpdateAction Action { get; init; }
+    public required int Index { get; init; }
+    public int? NewIndex { get; init; } = -1;
+    public required int Count { get; init; }
+    public required PlaylistSong[] Songs { get; init; } = [];
+}
\ No newline at end of file
diff --git a/Harmonia.Core/Extensions/EnumerableExtensions.cs b/Harmonia.Core/Extensions/EnumerableExtensions.cs
new file mode 100644
index 0000000..fb699cf
--- /dev/null
+++ b/Harmonia.Core/Extensions/EnumerableExtensions.cs
@@ -0,0 +1,34 @@
+using Harmonia.Core.Models;
+using System.ComponentModel;
+using System.Reflection;
+
+namespace Harmonia.Core.Extensions;
+
+public static class EnumerableExtensions
+{
+    public static IOrderedEnumerable<T> SortBy<T>(this IEnumerable<T> source, SortOption[] sortOptions)
+    {
+        IOrderedEnumerable<T> orderedQuery = source.OrderBy(x => 0);
+        Type type = typeof(T);
+
+        foreach (SortOption sortOption in sortOptions)
+        {
+            PropertyInfo? property = type.GetProperty(sortOption.FieldName);
+
+            if (property == null)
+                continue;
+
+            switch (sortOption.Direction)
+            {
+                case ListSortDirection.Ascending:
+                    orderedQuery = orderedQuery.ThenBy(x => property.GetValue(x));
+                    break;
+                case ListSortDirection.Descending:
+                    orderedQuery = orderedQuery.ThenByDescending(x => property.GetValue(x));
+                    break;
+            }
+        }
+
+        return orderedQuery;
+    }
+}
\ No newline at end of file
diff --git a/Harmonia.Core/Models/Playlist.cs b/Harmonia.Core/Models/Playlist.cs
index a886b4f..dafe6bd 100644
--- a/Harmonia.Core/Models/Playlist.cs
+++ b/Harmonia.Core/Models/Playlist.cs
@@ -1,4 +1,7 @@
-namespace Harmonia.Core.Models;
+using Harmonia.Core.Events;
+using Harmonia.Core.Extensions;
+
+namespace Harmonia.Core.Models;
 
 public class Playlist(string name)
 {
@@ -8,4 +11,161 @@ public class Playlist(string name)
     public List<GroupOption> GroupOptions { get; set; } = [];
     public List<SortOption> SortOptions { get; set; } = [];
     public bool IsLocked { get; set; }
+
+    public event EventHandler<PlaylistUpdatedEventArgs>? PlaylistUpdated;
+
+    public void AddSong(Song song, int? index)
+    {
+        AddSongs([song], index);
+    }
+
+    public void AddSongs(Song[] songs, int? index)
+    {
+        PlaylistSong[] playlistSongs = songs.Select(song => new PlaylistSong(song)).ToArray();
+
+        AddSongs(playlistSongs, index);
+    }
+
+    private void AddSongs(PlaylistSong[] playlistSongs, int? index)
+    {
+        if (IsLocked)
+            return;
+
+        int insertIndex = index ?? Songs.Count;
+
+        Songs.InsertRange(insertIndex, playlistSongs);
+
+        PlaylistUpdatedEventArgs eventArgs = new()
+        {
+            Action = PlaylistUpdateAction.Add,
+            Index = insertIndex,
+            Count = playlistSongs.Length,
+            Songs = playlistSongs
+        };
+
+        PlaylistUpdated?.Invoke(this, eventArgs);
+    }
+
+    public void MoveSong(PlaylistSong playlistSong, int newIndex)
+    {
+        int currentIndex = Songs.IndexOf(playlistSong);
+
+        MoveSong(currentIndex, newIndex);
+    }
+
+    public void MoveSong(int oldIndex, int newIndex)
+    {
+        if (IsLocked)
+            return;
+
+        if (oldIndex == newIndex)
+            return;
+
+        PlaylistSong playlistSong = Songs[oldIndex];
+
+        Songs.Remove(playlistSong);
+        Songs.Insert(newIndex, playlistSong);
+
+        PlaylistUpdatedEventArgs eventArgs = new()
+        {
+            Action = PlaylistUpdateAction.Move,
+            Index = oldIndex,
+            Count = 1,
+            Songs = [playlistSong],
+            NewIndex = newIndex
+        };
+
+        PlaylistUpdated?.Invoke(this, eventArgs);
+    }
+
+    public void SortSongs(PlaylistSong[] playlistSongs, SortOption[] sortOptions)
+    {
+        Dictionary<int, PlaylistSong> oldPlaylistSongs = playlistSongs
+            .OrderBy(Songs.IndexOf)
+            .ToDictionary(Songs.IndexOf, playlistSong => playlistSong);
+
+        Song[] songs = playlistSongs.Select(playlistSong => playlistSong.Song).ToArray();
+        Song[] sortedSongs = [.. songs.SortBy(sortOptions)];
+
+        int currentSortIndex = 0;
+
+        foreach (int index in oldPlaylistSongs.Keys)
+        {
+            PlaylistSong playlistSong = oldPlaylistSongs[index];
+            Song sortedSong = sortedSongs[currentSortIndex++];
+            PlaylistSong newPlaylistSong = playlistSongs.First(ps => ps.Song == sortedSong);
+
+            if (newPlaylistSong == playlistSong)
+                continue;
+
+            Songs.Remove(playlistSong);
+            Songs.Insert(index, newPlaylistSong);
+        }
+
+        PlaylistUpdatedEventArgs eventArgs = new()
+        {
+            Action = PlaylistUpdateAction.Reset,
+            Index = -1,
+            Count = playlistSongs.Length,
+            Songs = playlistSongs
+        };
+
+        PlaylistUpdated?.Invoke(this, eventArgs);
+    }
+
+    public void RemoveSong(int index)
+    {
+        RemoveSongs(index, 1);
+    }
+
+    public void RemoveSongs(int index, int count)
+    {
+        if (IsLocked)
+            return;
+
+        PlaylistSong[] playlistSongs = [.. Songs.GetRange(index, count)];
+
+        Songs.RemoveRange(index, count);
+
+        PlaylistUpdatedEventArgs eventArgs = new()
+        {
+            Action = PlaylistUpdateAction.Remove,
+            Index = index,
+            Count = count,
+            Songs = playlistSongs
+        };
+
+        PlaylistUpdated?.Invoke(this, eventArgs);
+    }
+
+    public void RemoveSong(PlaylistSong playlistSong)
+    {
+        RemoveSongs([playlistSong]);
+    }
+
+    public void RemoveSongs(PlaylistSong[] playlistSongs)
+    {
+        List<PlaylistSong> removedSongs = [];
+
+        foreach (PlaylistSong playlistSong in playlistSongs)
+        {
+            if (Songs.Remove(playlistSong))
+            {
+                removedSongs.Add(playlistSong);
+            }
+        }
+
+        if (removedSongs.Count == 0)
+            return;
+
+        PlaylistUpdatedEventArgs eventArgs = new()
+        {
+            Action = PlaylistUpdateAction.Remove,
+            Index = -1,
+            Count = removedSongs.Count,
+            Songs = playlistSongs
+        };
+
+        PlaylistUpdated?.Invoke(this, eventArgs);
+    }
 }
\ No newline at end of file