diff --git a/cartridges/ui/collections.py b/cartridges/ui/collections.py
new file mode 100644
index 0000000..e01eeec
--- /dev/null
+++ b/cartridges/ui/collections.py
@@ -0,0 +1,53 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+# SPDX-FileCopyrightText: Copyright 2025 Jamie Gravendeel
+
+from typing import Any, override
+
+from gi.repository import Adw, GObject, Gtk
+
+from cartridges.collections import Collection
+from cartridges.games import Game
+
+
+class CollectionFilter(Gtk.Filter):
+    """Filter games based on a selected collection."""
+
+    __gtype_name__ = __qualname__
+
+    @GObject.Property(type=Collection)
+    def collection(self) -> Collection | None:
+        """The collection used for filtering."""
+        return self._collection
+
+    @collection.setter
+    def collection(self, collection: Collection | None):
+        self._collection = collection
+        self.changed(Gtk.FilterChange.DIFFERENT)
+
+    @override
+    def do_match(self, game: Game) -> bool:  # pyright: ignore[reportIncompatibleMethodOverride]
+        if not self.collection:
+            return True
+
+        return game.game_id in self.collection.game_ids
+
+
+class CollectionSidebarItem(Adw.SidebarItem):  # pyright: ignore[reportAttributeAccessIssue]
+    """A sidebar item representing a collection."""
+
+    @GObject.Property(type=Collection)
+    def collection(self) -> Collection:
+        """The collection that `self` represents."""
+        return self._collection
+
+    @collection.setter
+    def collection(self, collection: Collection):
+        self._collection = collection
+        flags = GObject.BindingFlags.SYNC_CREATE
+        collection.bind_property("name", self, "title", flags)
+        collection.bind_property("icon-name", self, "icon-name", flags)
+
+    def __init__(self, **kwargs: Any):
+        super().__init__(**kwargs)
+
+        self.bind_property("title", self, "tooltip", GObject.BindingFlags.SYNC_CREATE)
diff --git a/cartridges/ui/meson.build b/cartridges/ui/meson.build
index cc2be3d..e430786 100644
--- a/cartridges/ui/meson.build
+++ b/cartridges/ui/meson.build
@@ -1,6 +1,7 @@
 python.install_sources(
     files(
         '__init__.py',
+        'collections.py',
         'cover.py',
         'game_details.py',
         'game_item.py',
diff --git a/cartridges/ui/shortcuts-dialog.blp b/cartridges/ui/shortcuts-dialog.blp
index ee518b1..51aa1dd 100644
--- a/cartridges/ui/shortcuts-dialog.blp
+++ b/cartridges/ui/shortcuts-dialog.blp
@@ -10,6 +10,11 @@ Adw.ShortcutsDialog shortcuts_dialog {
       accelerator: "<Control>f";
     }
 
+    Adw.ShortcutsItem {
+      title: _("Toggle Sidebar");
+      accelerator: "F9";
+    }
+
     Adw.ShortcutsItem {
       title: _("Main Menu");
       accelerator: "F10";
diff --git a/cartridges/ui/window.blp b/cartridges/ui/window.blp
index 8ef9fe5..2ee440e 100644
--- a/cartridges/ui/window.blp
+++ b/cartridges/ui/window.blp
@@ -26,12 +26,25 @@ template $Window: Adw.ApplicationWindow {
       action: "action(win.undo)";
     }
 
+    Shortcut {
+      trigger: "F9";
+      action: "action(win.show-sidebar)";
+    }
+
     Shortcut {
       trigger: "<Control>w";
       action: "action(window.close)";
     }
   }
 
+  Adw.Breakpoint {
+    condition ("max-width: 730px") // 3 columns + 48px of inherent padding
+
+    setters {
+      split_view.collapsed: true;
+    }
+  }
+
   content: Adw.NavigationView navigation_view {
     Adw.NavigationPage {
       title: bind template.title;
@@ -41,198 +54,267 @@ template $Window: Adw.ApplicationWindow {
         "view",
       ]
 
-      child: Adw.ToolbarView {
-        [top]
-        Adw.HeaderBar header_bar {
-          title-widget: Adw.Clamp clamp {
-            tightening-threshold: bind clamp.maximum-size;
+      child: Adw.OverlaySplitView split_view {
+        sidebar-width-unit: px;
+        min-sidebar-width: 224; // Width of 1 column
+        max-sidebar-width: bind split_view.min-sidebar-width;
 
-            child: CenterBox title_box {
-              hexpand: true;
+        sidebar: Adw.NavigationPage {
+          title: bind template.title;
 
-              center-widget: SearchEntry search_entry {
-                hexpand: true;
-                placeholder-text: _("Search games");
-                search-started => $_search_started();
-                search-changed => $_search_changed();
-                activate => $_search_activate();
-                stop-search => $_stop_search();
-              };
+          child: Adw.ToolbarView {
+            [top]
+            Adw.HeaderBar {
+              show-title: bind $_show_sidebar_title(template.settings as <Settings>.gtk-decoration-layout) as <bool>;
 
-              end-widget: MenuButton sort_button {
-                icon-name: "filter-symbolic";
-                tooltip-text: _("Sort & Filter");
-                margin-start: 6;
+              [start]
+              Button {
+                visible: bind split_view.show-sidebar;
+                action-name: "win.show-sidebar";
+                icon-name: "sidebar-show-symbolic";
+                tooltip-text: _("Toggle Sidebar");
+              }
+            }
 
-                menu-model: menu {
-                  section {
-                    label: _("Sort");
+            content: Adw.Sidebar sidebar {
+              activated => $_navigate();
 
-                    item {
-                      label: _("Last Played");
-                      action: "win.sort-mode";
-                      target: "last_played";
-                    }
+              Adw.SidebarSection {
+                Adw.SidebarItem {
+                  icon-name: "view-grid-symbolic";
+                  title: _("All Games");
+                }
+              }
 
-                    item {
-                      label: _("A-Z");
-                      action: "win.sort-mode";
-                      target: "a-z";
-                    }
-
-                    item {
-                      label: _("Z-A");
-                      action: "win.sort-mode";
-                      target: "z-a";
-                    }
-
-                    item {
-                      label: _("Newest");
-                      action: "win.sort-mode";
-                      target: "newest";
-                    }
-
-                    item {
-                      label: _("Oldest");
-                      action: "win.sort-mode";
-                      target: "oldest";
-                    }
-                  }
-
-                  section {
-                    item (_("Show Hidden Games"), "win.show-hidden")
-                  }
-                };
-              };
+              Adw.SidebarSection collections {
+                title: _("Collections");
+              }
             };
           };
+        };
 
-          [start]
-          Button {
-            icon-name: "list-add-symbolic";
-            tooltip-text: _("Add Game");
-            action-name: "win.add";
-          }
+        content: Adw.NavigationPage {
+          title: _("Games");
 
-          [end]
-          MenuButton main_menu_button {
-            icon-name: "open-menu-symbolic";
-            tooltip-text: _("Main Menu");
-            primary: true;
+          child: Adw.ToolbarView {
+            [top]
+            Adw.HeaderBar header_bar {
+              title-widget: Adw.Clamp clamp {
+                tightening-threshold: bind clamp.maximum-size;
 
-            menu-model: menu {
-              item (_("Keyboard Shortcuts"), "app.shortcuts")
-              item (_("About Cartridges"), "app.about")
-            };
-          }
-        }
+                child: CenterBox title_box {
+                  hexpand: true;
 
-        content: Adw.ToastOverlay toast_overlay {
-          child: Adw.ViewStack {
-            enable-transitions: true;
-            visible-child-name: bind $_if_else(
-              grid.model as <NoSelection>.n-items,
-              "grid",
-              $_if_else(
-                template.search-text,
-                "empty-search",
-                $_if_else(template.show-hidden, "empty-hidden", "empty") as <string>
-              ) as <string>
-            ) as <string>;
+                  center-widget: SearchEntry search_entry {
+                    hexpand: true;
+                    placeholder-text: _("Search games");
+                    search-started => $_search_started();
+                    search-changed => $_search_changed();
+                    activate => $_search_activate();
+                    stop-search => $_stop_search();
+                  };
 
-            Adw.ViewStackPage {
-              name: "grid";
+                  end-widget: MenuButton sort_button {
+                    icon-name: "filter-symbolic";
+                    tooltip-text: _("Sort & Filter");
+                    margin-start: 6;
 
-              child: ScrolledWindow {
-                hscrollbar-policy: never;
+                    menu-model: menu {
+                      section {
+                        label: _("Sort");
 
-                child: GridView grid {
+                        item {
+                          label: _("Last Played");
+                          action: "win.sort-mode";
+                          target: "last_played";
+                        }
+
+                        item {
+                          label: _("A-Z");
+                          action: "win.sort-mode";
+                          target: "a-z";
+                        }
+
+                        item {
+                          label: _("Z-A");
+                          action: "win.sort-mode";
+                          target: "z-a";
+                        }
+
+                        item {
+                          label: _("Newest");
+                          action: "win.sort-mode";
+                          target: "newest";
+                        }
+
+                        item {
+                          label: _("Oldest");
+                          action: "win.sort-mode";
+                          target: "oldest";
+                        }
+                      }
+
+                      section {
+                        item (_("Show Hidden Games"), "win.show-hidden")
+                      }
+                    };
+                  };
+                };
+              };
+
+              [start]
+              Button {
+                visible: bind split_view.show-sidebar inverted;
+                action-name: "win.show-sidebar";
+                icon-name: "sidebar-show-symbolic";
+                tooltip-text: _("Toggle Sidebar");
+              }
+
+              [start]
+              Button {
+                icon-name: "list-add-symbolic";
+                tooltip-text: _("Add Game");
+                action-name: "win.add";
+              }
+
+              [end]
+              MenuButton main_menu_button {
+                icon-name: "open-menu-symbolic";
+                tooltip-text: _("Main Menu");
+                primary: true;
+
+                menu-model: menu {
+                  item (_("Keyboard Shortcuts"), "app.shortcuts")
+                  item (_("About Cartridges"), "app.about")
+                };
+              }
+            }
+
+            content: Adw.ToastOverlay toast_overlay {
+              child: Adw.ViewStack {
+                enable-transitions: true;
+                visible-child-name: bind $_if_else(
+                  grid.model as <NoSelection>.n-items,
+                  "grid",
+                  $_if_else(
+                    template.search-text,
+                    "empty-search",
+                    $_if_else(
+                      template.show-hidden,
+                      "empty-hidden",
+                      $_if_else(template.collection, "empty-collection", "empty") as <string>
+                    ) as <string>
+                  ) as <string>
+                ) as <string>;
+
+                Adw.ViewStackPage {
                   name: "grid";
-                  single-click-activate: true;
-                  activate => $_show_details();
 
-                  model: NoSelection {
-                    model: SortListModel {
-                      sorter: $GameSorter sorter {};
+                  child: ScrolledWindow {
+                    hscrollbar-policy: never;
 
-                      model: FilterListModel {
-                        watch-items: true;
+                    child: GridView grid {
+                      name: "grid";
+                      single-click-activate: true;
+                      activate => $_show_details();
 
-                        filter: EveryFilter {
-                          AnyFilter {
-                            StringFilter {
-                              expression: expr item as <$Game>.name;
-                              search: bind template.search-text;
-                            }
+                      model: NoSelection {
+                        model: SortListModel {
+                          sorter: $GameSorter sorter {};
 
-                            StringFilter {
-                              expression: expr item as <$Game>.developer;
-                              search: bind template.search-text;
-                            }
-                          }
+                          model: FilterListModel {
+                            watch-items: true;
 
-                          BoolFilter {
-                            expression: expr item as <$Game>.hidden;
-                            invert: bind template.show-hidden inverted;
-                          }
+                            filter: EveryFilter {
+                              $CollectionFilter {
+                                collection: bind template.collection;
+                              }
 
-                          BoolFilter {
-                            expression: expr item as <$Game>.removed;
-                            invert: true;
-                          }
+                              AnyFilter {
+                                StringFilter {
+                                  expression: expr item as <$Game>.name;
+                                  search: bind template.search-text;
+                                }
 
-                          BoolFilter {
-                            expression: expr item as <$Game>.blacklisted;
-                            invert: true;
-                          }
+                                StringFilter {
+                                  expression: expr item as <$Game>.developer;
+                                  search: bind template.search-text;
+                                }
+                              }
+
+                              BoolFilter {
+                                expression: expr item as <$Game>.hidden;
+                                invert: bind template.show-hidden inverted;
+                              }
+
+                              BoolFilter {
+                                expression: expr item as <$Game>.removed;
+                                invert: true;
+                              }
+
+                              BoolFilter {
+                                expression: expr item as <$Game>.blacklisted;
+                                invert: true;
+                              }
+                            };
+
+                            model: bind template.games;
+                          };
                         };
+                      };
 
-                        model: bind template.games;
+                      factory: BuilderListItemFactory {
+                        template ListItem {
+                          child: $GameItem {
+                            game: bind template.item;
+                            position: bind template.position;
+                          };
+                        }
                       };
                     };
                   };
+                }
 
-                  factory: BuilderListItemFactory {
-                    template ListItem {
-                      child: $GameItem {
-                        game: bind template.item;
-                        position: bind template.position;
-                      };
-                    }
+                Adw.ViewStackPage {
+                  name: "empty-search";
+
+                  child: Adw.StatusPage {
+                    icon-name: "edit-find-symbolic";
+                    title: _("No Games Found");
+                    description: _("Try a different search");
                   };
-                };
+                }
+
+                Adw.ViewStackPage {
+                  name: "empty-hidden";
+
+                  child: Adw.StatusPage {
+                    icon-name: "view-conceal-symbolic";
+                    title: _("No Hidden Games");
+                    description: _("Games you hide will appear here");
+                  };
+                }
+
+                Adw.ViewStackPage {
+                  name: "empty-collection";
+
+                  child: Adw.StatusPage {
+                    icon-name: bind template.collection as <$Collection>.icon-name;
+                    title: bind $_format(_("No Games in {}"), template.collection as <$Collection>.name) as <string>;
+                  };
+                }
+
+                Adw.ViewStackPage {
+                  name: "empty";
+
+                  child: Adw.StatusPage {
+                    icon-name: bind template.application as <Application>.application-id;
+                    title: _("No Games");
+                    description: _("Use the + button to add games");
+                  };
+                }
               };
-            }
-
-            Adw.ViewStackPage {
-              name: "empty-search";
-
-              child: Adw.StatusPage {
-                icon-name: "edit-find-symbolic";
-                title: _("No Games Found");
-                description: _("Try a different search");
-              };
-            }
-
-            Adw.ViewStackPage {
-              name: "empty-hidden";
-
-              child: Adw.StatusPage {
-                icon-name: "view-conceal-symbolic";
-                title: _("No Hidden Games");
-                description: _("Games you hide will appear here");
-              };
-            }
-
-            Adw.ViewStackPage {
-              name: "empty";
-
-              child: Adw.StatusPage {
-                icon-name: bind template.application as <Application>.application-id;
-                title: _("No Games");
-                description: _("Use the + button to add games");
-              };
-            }
+            };
           };
         };
       };
diff --git a/cartridges/ui/window.py b/cartridges/ui/window.py
index 7f953c4..e2b9aef 100644
--- a/cartridges/ui/window.py
+++ b/cartridges/ui/window.py
@@ -10,10 +10,15 @@ from typing import Any, TypeVar, cast
 
 from gi.repository import Adw, Gio, GLib, GObject, Gtk
 
-from cartridges import games, state_settings
+from cartridges import collections, games, state_settings
+from cartridges.collections import Collection
 from cartridges.config import PREFIX, PROFILE
 from cartridges.games import Game
 
+from .collections import (
+    CollectionFilter,  # noqa: F401
+    CollectionSidebarItem,
+)
 from .game_details import GameDetails
 from .game_item import GameItem  # noqa: F401
 from .games import GameSorter
@@ -40,6 +45,8 @@ class Window(Adw.ApplicationWindow):
 
     __gtype_name__ = __qualname__
 
+    split_view: Adw.OverlaySplitView = Gtk.Template.Child()
+    collections: Adw.SidebarSection = Gtk.Template.Child()  # pyright: ignore[reportAttributeAccessIssue]
     navigation_view: Adw.NavigationView = Gtk.Template.Child()
     header_bar: Adw.HeaderBar = Gtk.Template.Child()
     title_box: Gtk.CenterBox = Gtk.Template.Child()
@@ -53,6 +60,9 @@ class Window(Adw.ApplicationWindow):
 
     search_text = GObject.Property(type=str)
     show_hidden = GObject.Property(type=bool, default=False)
+    collection = GObject.Property(type=Collection)
+
+    settings = GObject.Property(type=Gtk.Settings)
 
     @GObject.Property(type=Gio.ListStore)
     def games(self) -> Gio.ListStore:
@@ -65,14 +75,22 @@ class Window(Adw.ApplicationWindow):
         if PROFILE == "development":
             self.add_css_class("devel")
 
+        self.settings = self.get_settings()
+
         flags = Gio.SettingsBindFlags.DEFAULT
         state_settings.bind("width", self, "default-width", flags)
         state_settings.bind("height", self, "default-height", flags)
         state_settings.bind("is-maximized", self, "maximized", flags)
+        state_settings.bind("show-sidebar", self.split_view, "show-sidebar", flags)
 
         # https://gitlab.gnome.org/GNOME/gtk/-/issues/7901
         self.search_entry.set_key_capture_widget(self)
+        self.collections.bind_model(
+            collections.model,
+            lambda collection: CollectionSidebarItem(collection=collection),
+        )
 
+        self.add_action(state_settings.create_action("show-sidebar"))
         self.add_action(state_settings.create_action("sort-mode"))
         self.add_action(Gio.PropertyAction.new("show-hidden", self, "show-hidden"))
         self.add_action_entries((
@@ -102,6 +120,18 @@ class Window(Adw.ApplicationWindow):
 
         self.toast_overlay.add_toast(toast)
 
+    @Gtk.Template.Callback()
+    def _show_sidebar_title(self, _obj, layout: str) -> bool:
+        right_window_controls = layout.replace("appmenu", "").startswith(":")
+        return right_window_controls and not sys.platform.startswith("darwin")
+
+    @Gtk.Template.Callback()
+    def _navigate(self, sidebar: Adw.Sidebar, index: int):  # pyright: ignore[reportAttributeAccessIssue]
+        item = sidebar.get_item(index)
+        self.collection = (
+            item.collection if isinstance(item, CollectionSidebarItem) else None
+        )
+
     @Gtk.Template.Callback()
     def _setup_gamepad_monitor(self, *_args):
         if sys.platform.startswith("linux"):
@@ -112,6 +142,10 @@ class Window(Adw.ApplicationWindow):
     def _if_else(self, _obj, condition: object, first: _T, second: _T) -> _T:
         return first if condition else second
 
+    @Gtk.Template.Callback()
+    def _format(self, _obj, string: str, *args: Any) -> str:
+        return string.format(*args)
+
     @Gtk.Template.Callback()
     def _show_details(self, grid: Gtk.GridView, position: int):
         self.details.game = cast(Gio.ListModel, grid.props.model).get_item(position)
diff --git a/data/icons/icons.gresource.xml.in b/data/icons/icons.gresource.xml.in
index 7805cc5..872fbbc 100644
--- a/data/icons/icons.gresource.xml.in
+++ b/data/icons/icons.gresource.xml.in
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="UTF-8" ?>
 <gresources>
   <gresource prefix="@PREFIX@/icons/scalable/actions">
+    <file>collection-symbolic.svg</file>
     <file>filter-symbolic.svg</file>
   </gresource>
 </gresources>
diff --git a/data/page.kramo.Cartridges.gschema.xml.in b/data/page.kramo.Cartridges.gschema.xml.in
index 97bf8cb..042dcea 100644
--- a/data/page.kramo.Cartridges.gschema.xml.in
+++ b/data/page.kramo.Cartridges.gschema.xml.in
@@ -25,5 +25,8 @@
       </choices>
       <default>"last_played"</default>
     </key>
+    <key name="show-sidebar" type="b">
+      <default>false</default>
+    </key>
   </schema>
 </schemalist>
diff --git a/po/POTFILES.in b/po/POTFILES.in
index 3417e4d..b584dda 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -4,6 +4,7 @@ cartridges/gamepads.py
 cartridges/games.py
 cartridges/sources/__init__.py
 cartridges/sources/steam.py
+cartridges/ui/collections.py
 cartridges/ui/cover.blp
 cartridges/ui/cover.py
 cartridges/ui/game-details.blp
diff --git a/pyproject.toml b/pyproject.toml
index 6e5be6a..cd028cf 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -22,6 +22,7 @@ reportUnknownLambdaType = "none"
 reportUnknownMemberType = "none"
 reportUnknownParameterType = "none"
 reportUnknownVariableType = "none"
+reportUntypedBaseClass = "none"
 reportUntypedFunctionDecorator = "none"
 reportUnusedImport = "none"
 reportUnusedVariable = "none"