diff --git a/crates/editor/src/editor.rs b/crates/editor/src/editor.rs
index a4d9259a6d..ab952ba6e7 100644
--- a/crates/editor/src/editor.rs
+++ b/crates/editor/src/editor.rs
@@ -231,6 +231,8 @@ actions!(
         SortLinesCaseInsensitive,
         ReverseLines,
         ShuffleLines,
+        ConvertToUpperCase,
+        ConvertToLowerCase,
         Transpose,
         Cut,
         Copy,
@@ -353,6 +355,8 @@ pub fn init(cx: &mut AppContext) {
     cx.add_action(Editor::sort_lines_case_insensitive);
     cx.add_action(Editor::reverse_lines);
     cx.add_action(Editor::shuffle_lines);
+    cx.add_action(Editor::convert_to_upper_case);
+    cx.add_action(Editor::convert_to_lower_case);
     cx.add_action(Editor::delete_to_previous_word_start);
     cx.add_action(Editor::delete_to_previous_subword_start);
     cx.add_action(Editor::delete_to_next_word_end);
@@ -4306,6 +4310,68 @@ impl Editor {
         });
     }
 
+    pub fn convert_to_upper_case(&mut self, _: &ConvertToUpperCase, cx: &mut ViewContext<Self>) {
+        self.manipulate_text(cx, |text| text.to_uppercase())
+    }
+
+    pub fn convert_to_lower_case(&mut self, _: &ConvertToLowerCase, cx: &mut ViewContext<Self>) {
+        self.manipulate_text(cx, |text| text.to_lowercase())
+    }
+
+    fn manipulate_text<Fn>(&mut self, cx: &mut ViewContext<Self>, mut callback: Fn)
+    where
+        Fn: FnMut(&str) -> String,
+    {
+        let display_map = self.display_map.update(cx, |map, cx| map.snapshot(cx));
+        let buffer = self.buffer.read(cx).snapshot(cx);
+
+        let mut new_selections = Vec::new();
+        let mut edits = Vec::new();
+        for selection in self.selections.all::<usize>(cx) {
+            let selection_is_empty = selection.is_empty();
+
+            let (start, end) = if selection_is_empty {
+                let word_range = movement::surrounding_word(
+                    &display_map,
+                    selection.start.to_display_point(&display_map),
+                );
+                let start = word_range.start.to_offset(&display_map, Bias::Left);
+                let end = word_range.end.to_offset(&display_map, Bias::Left);
+                (start, end)
+            } else {
+                (selection.start, selection.end)
+            };
+
+            let text = buffer.text_for_range(start..end).collect::<String>();
+            let text = callback(&text);
+
+            if selection_is_empty {
+                new_selections.push(selection);
+            } else {
+                new_selections.push(Selection {
+                    start,
+                    end: start + text.len(),
+                    goal: SelectionGoal::None,
+                    ..selection
+                });
+            }
+
+            edits.push((start..end, text));
+        }
+
+        self.transact(cx, |this, cx| {
+            this.buffer.update(cx, |buffer, cx| {
+                buffer.edit(edits, None, cx);
+            });
+
+            this.change_selections(Some(Autoscroll::fit()), cx, |s| {
+                s.select(new_selections);
+            });
+
+            this.request_autoscroll(Autoscroll::fit(), cx);
+        });
+    }
+
     pub fn duplicate_line(&mut self, _: &DuplicateLine, cx: &mut ViewContext<Self>) {
         let display_map = self.display_map.update(cx, |map, cx| map.snapshot(cx));
         let buffer = &display_map.buffer_snapshot;
diff --git a/crates/editor/src/editor_tests.rs b/crates/editor/src/editor_tests.rs
index e8913505ca..11d64f085c 100644
--- a/crates/editor/src/editor_tests.rs
+++ b/crates/editor/src/editor_tests.rs
@@ -2695,6 +2695,65 @@ async fn test_manipulate_lines_with_multi_selection(cx: &mut TestAppContext) {
     "});
 }
 
+#[gpui::test]
+async fn test_manipulate_text(cx: &mut TestAppContext) {
+    init_test(cx, |_| {});
+
+    let mut cx = EditorTestContext::new(cx).await;
+
+    // Test convert_to_upper_case()
+    cx.set_state(indoc! {"
+        «hello worldˇ»
+    "});
+    cx.update_editor(|e, cx| e.convert_to_upper_case(&ConvertToUpperCase, cx));
+    cx.assert_editor_state(indoc! {"
+        «HELLO WORLDˇ»
+    "});
+
+    // Test convert_to_lower_case()
+    cx.set_state(indoc! {"
+        «HELLO WORLDˇ»
+    "});
+    cx.update_editor(|e, cx| e.convert_to_lower_case(&ConvertToLowerCase, cx));
+    cx.assert_editor_state(indoc! {"
+        «hello worldˇ»
+    "});
+
+    // From here on out, test more complex cases of manipulate_text() with a single driver method: convert_to_upper_case()
+
+    // Test no selection case - should affect words cursors are in
+    // Cursor at beginning, middle, and end of word
+    cx.set_state(indoc! {"
+        ˇhello big beauˇtiful worldˇ
+    "});
+    cx.update_editor(|e, cx| e.convert_to_upper_case(&ConvertToUpperCase, cx));
+    cx.assert_editor_state(indoc! {"
+        ˇHELLO big BEAUˇTIFUL WORLDˇ
+    "});
+
+    // Test multiple selections on a single line and across multiple lines
+    cx.set_state(indoc! {"
+        «Theˇ» quick «brown
+        foxˇ» jumps «overˇ»
+        the «lazyˇ» dog
+    "});
+    cx.update_editor(|e, cx| e.convert_to_upper_case(&ConvertToUpperCase, cx));
+    cx.assert_editor_state(indoc! {"
+        «THEˇ» quick «BROWN
+        FOXˇ» jumps «OVERˇ»
+        the «LAZYˇ» dog
+    "});
+
+    // Test case where text length grows
+    cx.set_state(indoc! {"
+        «tschüߡ»
+    "});
+    cx.update_editor(|e, cx| e.convert_to_upper_case(&ConvertToUpperCase, cx));
+    cx.assert_editor_state(indoc! {"
+        «TSCHÜSSˇ»
+    "});
+}
+
 #[gpui::test]
 fn test_duplicate_line(cx: &mut TestAppContext) {
     init_test(cx, |_| {});