diff --git a/assets/highlighting-tests/csharp.cs b/assets/highlighting-tests/csharp.cs
new file mode 100644
index 00000000000..9b139bf087a
--- /dev/null
+++ b/assets/highlighting-tests/csharp.cs
@@ -0,0 +1,65 @@
+// Single-line comment
+/* Block comment
+   spanning multiple lines */
+
+using System;
+using System.Collections.Generic;
+
+#nullable enable
+
+namespace Demo.App;
+
+[Obsolete("Use NewThing instead")]
+public sealed class Greeter
+{
+    private readonly string _name;
+
+    public Greeter(string name)
+    {
+        _name = name;
+    }
+
+    public string SayHello(int count = 3)
+    {
+        var list = new List<int> { 1, 2, 3 };
+        var pi = 3.14159;
+        var hex = 0xDEAD_BEEF;
+
+        // Regular string
+        var a = "Hello, \"world\"";
+
+        // Verbatim string
+        var b = @"C:\\Temp\\file.txt";
+
+        // Interpolated string
+        var c = $"Hello {_name}, count={count}";
+
+        // Interpolated string with alignment + format specifier
+        var c2 = $"Name={_name,-10} Count={count:D2}";
+
+        // Interpolated verbatim string
+        var d = $@"Name={_name}\nCount={count}";
+
+        // Escaped literal braces in interpolated string (should stay string-colored)
+        var d2 = $"Literal braces: {{ and }}";
+
+        return c;
+    }
+}
+
+public record Person(string Name, int Age);
+
+public static class Program
+{
+    public static int Main(string[] args)
+    {
+        if (args.Length == 0)
+        {
+            return 1;
+        }
+
+        var g = new Greeter(args[0]);
+        Console.WriteLine(g.SayHello());
+        return 0;
+    }
+}
diff --git a/assets/highlighting-tests/markdown.md b/assets/highlighting-tests/markdown.md
index 555b182f961..b0ecfbf1d1f 100644
--- a/assets/highlighting-tests/markdown.md
+++ b/assets/highlighting-tests/markdown.md
@@ -84,3 +84,10 @@ export function greet(name) {
 def greet(name: str) -> str:
     return f"hello {name}"
 ```
+
+```CSharp
+public string Greet(string name)
+{
+  return $"hello {name}";
+}
+```
diff --git a/crates/edit/src/buffer/mod.rs b/crates/edit/src/buffer/mod.rs
index 9277192e500..e1e86a63a0f 100644
--- a/crates/edit/src/buffer/mod.rs
+++ b/crates/edit/src/buffer/mod.rs
@@ -2187,6 +2187,7 @@ impl TextBuffer {
                     HighlightKind::MarkupList => Some(IndexedColor::BrightBlue),
                     HighlightKind::MarkupStrikethrough => None,
                     HighlightKind::MetaHeader => Some(IndexedColor::BrightBlue),
+                    HighlightKind::MetaPreprocessor => Some(IndexedColor::BrightBlue),
                 };
                 let attr = match curr.kind {
                     HighlightKind::MarkupBold => Some(Attributes::Bold),
diff --git a/crates/lsh-bin/src/main.rs b/crates/lsh-bin/src/main.rs
index 68547c431d5..cf341cbacac 100644
--- a/crates/lsh-bin/src/main.rs
+++ b/crates/lsh-bin/src/main.rs
@@ -136,6 +136,7 @@ fn run_render(generator: lsh::compiler::Generator, path: &Path) -> anyhow::Resul
             "markup.list" => "\x1b[94m",         // Bright Blue
             "markup.strikethrough" => "\x1b[9m", // Strikethrough
             "meta.header" => "\x1b[94m",         // Bright Blue
+            "meta.preprocessor" => "\x1b[94m",   // Bright Blue
 
             _ => {
                 unknown_kinds.push(hk.identifier.to_string());
diff --git a/crates/lsh/definitions/csharp.lsh b/crates/lsh/definitions/csharp.lsh
new file mode 100644
index 00000000000..ce697b2252a
--- /dev/null
+++ b/crates/lsh/definitions/csharp.lsh
@@ -0,0 +1,158 @@
+#[display_name = "C#"]
+#[path = "**/*.cs"]
+#[path = "**/*.csx"]
+pub fn csharp() {
+    // Preprocessor directives (entire line)
+    if /\s*#\s*(?:if|elif|else|endif|define|undef|warning|error|line|nullable|region|endregion|pragma)\>.*/ {
+        yield meta.preprocessor;
+        return;
+    }
+
+    until /$/ {
+        yield other;
+
+        if /\/\/.*/ {
+            yield comment;
+        } else if /\/\*/ {
+            loop {
+                yield comment;
+                await input;
+                if /\*\// {
+                    yield comment;
+                    break;
+                }
+            }
+        } else if /(?:\$@|@\$)"/ {
+            // Interpolated verbatim string: $@"..." or @$"..."
+            loop {
+                yield string;
+                if /""/ {
+                    // Escaped quote in verbatim strings
+                } else if /\{\{/ {
+                    // Escaped literal '{'
+                } else if /\}\}/ {
+                    // Escaped literal '}'
+                } else if /(\{)/ {
+                    // Interpolation start: braces default, contents light blue.
+                    yield $1 as other;
+                    yield constant.language;
+
+                    loop {
+                        if /(\})/ {
+                            yield $1 as other;
+                            break;
+                        } else if /[^}:,]+/ {
+                            // Interpolation contents (up to ':' or '}')
+                            yield constant.language;
+                        } else if /,\s*[^}:]+/ {
+                            // Alignment specifier: , -10, ,10, etc.
+                            yield constant.numeric;
+                            yield constant.language;
+                        } else if /:[^}]+/ {
+                            // Format specifier: :D2, :X, :N0, etc.
+                            yield constant.numeric;
+                            yield constant.language;
+                        } else {
+                            break;
+                        }
+                    }
+
+                    // Resume string highlighting
+                    yield string;
+                } else if /"/ {
+                    yield string;
+                    break;
+                }
+                await input;
+            }
+        } else if /@"/ {
+            // Verbatim string: @"..."
+            loop {
+                yield string;
+                if /""/ {
+                    // Escaped quote in verbatim strings
+                } else if /"/ {
+                    yield string;
+                    break;
+                }
+                await input;
+            }
+        } else if /\$"/ {
+            // Interpolated string: $"..."
+            until /$/ {
+                yield string;
+                if /\\./ {
+                } else if /\{\{/ {
+                    // Escaped literal '{'
+                } else if /\}\}/ {
+                    // Escaped literal '}'
+                } else if /(\{)/ {
+                    // Interpolation start: highlight braces as default, contents as light blue.
+                    yield $1 as other;
+                    yield constant.language;
+
+                    loop {
+                        if /(\})/ {
+                            yield $1 as other;
+                            break;
+                        } else if /[^}:,]+/ {
+                            // Interpolation contents (up to ':' or '}')
+                            yield constant.language;
+                        } else if /,\s*[^}:]+/ {
+                            // Alignment specifier: , -10, ,10, etc.
+                            yield constant.numeric;
+                            yield constant.language;
+                        } else if /:[^}]+/ {
+                            // Format specifier: :D2, :X, :N0, etc.
+                            yield constant.numeric;
+                            yield constant.language;
+                        } else {
+                            break;
+                        }
+                    }
+
+                    // Resume string highlighting
+                    yield string;
+                } else if /"/ {
+                    yield string;
+                    break;
+                }
+                await input;
+            }
+        } else if /"/ {
+            until /$/ {
+                yield string;
+                if /\\./ {}
+                else if /"/ { yield string; break; }
+                await input;
+            }
+        } else if /'/ {
+            // Character literal
+            until /$/ {
+                yield string;
+                if /\\./ {}
+                else if /'/ { yield string; break; }
+                await input;
+            }
+        } else if /\[(?:assembly:|module:)?\s*([A-Z]\w*)(?:Attribute)?/ {
+            // Attribute names like [Obsolete]
+            yield $1 as markup.link;
+        } else if /(?:break|case|catch|continue|default|do|else|finally|for|foreach|goto|if|return|switch|throw|try|while|yield)\>/ {
+            yield keyword.control;
+        } else if /(?:abstract|as|await|base|bool|byte|char|checked|class|const|decimal|delegate|dynamic|enum|event|explicit|extern|false|fixed|float|from|get|global|group|implicit|in|int|interface|internal|into|is|join|let|lock|long|nameof|namespace|new|null|object|operator|orderby|out|override|params|partial|private|protected|public|readonly|record|ref|required|sbyte|sealed|select|set|short|sizeof|stackalloc|static|string|struct|this|true|typeof|uint|ulong|unmanaged|unchecked|unsafe|ushort|using|var|virtual|void|volatile|where|with)\>/ {
+            yield keyword.other;
+        } else if /(?i:-?(?:0x[\da-fA-F_]+|0b[01_]+|0o[0-7_]+|[\d_]+\.?[\d_]*|\.[\d_]+)(?:e[+-]?[\d_]+)?)/ {
+            if /\w+/ {
+                // Invalid numeric literal
+            } else {
+                yield constant.numeric;
+            }
+        } else if /(\w+)\s*\(/ {
+            yield $1 as method;
+        } else if /\w+/ {
+            // Gobble word chars to align the next iteration on a word boundary.
+        }
+
+        yield other;
+    }
+}