diff --git a/assets/highlighting-tests/ruby.rb b/assets/highlighting-tests/ruby.rb
new file mode 100644
index 00000000000..d8e4cc25af2
--- /dev/null
+++ b/assets/highlighting-tests/ruby.rb
@@ -0,0 +1,133 @@
+# Single-line comment
+
+=begin
+Multi-line comment
+=end
+
+=begin rdoc
+The rest of the `=begin` line is ignored by Ruby.
+=end
+
+# Numbers
+42
+3.14
+0.5
+1e10
+1.5e-3
+0xff
+0xFF
+0b1010
+0o77
+1_000_000
+3.14r
+2i
+1.upto(3)
+(1..3).to_a
+(1...3).to_a
+
+# Constants
+true
+false
+nil
+Object
+String
+Demo::Animal
+::Kernel
+MAX_SIZE = 10
+
+# Strings
+'single quotes with escape: \' \n \t \\'
+"double quotes with escape: \" \n \t \\"
+"interpolated: #{1 + 1} and a # that is not a comment"
+`echo shell command`
+
+# Symbols and variables
+:symbol
+:method_name?
+attr_accessor :name, :age
+@instance_var
+@@class_var
+$global_var
+{ key: 'value' }
+
+# Control flow keywords
+if true
+  puts "yes"
+elsif false
+  puts "no"
+else
+  puts "maybe"
+end
+
+unless nil
+  puts "not nil"
+end
+
+case 42
+when 1
+  puts "one"
+else
+  puts "other"
+end
+
+for i in 1..3
+  next if i == 2
+  break if i == 3
+end
+
+while false
+  redo
+end
+
+until true
+  puts "spin"
+end
+
+begin
+  raise "oops"
+rescue StandardError => e
+  retry
+ensure
+  puts e
+end
+
+puts "even" if 42.even? and not false
+puts "odd" or true
+
+# Definitions and method calls
+module Demo
+  class Animal
+    def initialize(name)
+      @name = name
+    end
+
+    def self.create(name)
+      new(name)
+    end
+
+    def ==(other)
+      @name == other.name
+    end
+
+    def name=(value)
+      @name = value
+    end
+
+    def speak! = puts "#{@name} speaks"
+  end
+end
+
+alias old_speak speak!
+undef old_speak
+
+BEGIN { puts "start" }
+END { puts "finish" }
+defined? Demo
+puts __FILE__, __LINE__
+self
+super
+yield
+
+puts "hello"
+Array.new(3)
+greet("world")
diff --git a/crates/lsh/definitions/ruby.lsh b/crates/lsh/definitions/ruby.lsh
new file mode 100644
index 00000000000..ddc3973f01c
--- /dev/null
+++ b/crates/lsh/definitions/ruby.lsh
@@ -0,0 +1,77 @@
+#[display_name = "Ruby"]
+#[path = "**/*.gemspec"]
+#[path = "**/*.rake"]
+#[path = "**/*.rb"]
+#[path = "**/*.ru"]
+#[path = "**/Gemfile"]
+#[path = "**/Rakefile"]
+pub fn ruby() {
+    if /=begin\>.*/ {
+        loop {
+            yield comment;
+            await input;
+            if /=end\>.*/ {
+                yield comment;
+                break;
+            }
+            if /.*/ {}
+        }
+        return;
+    }
+
+    until /$/ {
+        yield other;
+
+        if /#.*/ {
+            yield comment;
+        } else if /'/ {
+            single_quote_string();
+        } else if /"/ {
+            double_quote_string();
+        } else if /`/ {
+            until /$/ {
+                if /\\./ {
+                    // Escape sequences
+                } else if /`/ {
+                    yield string;
+                    break;
+                }
+            }
+        } else if /(?:begin|break|case|do|elsif|else|end|ensure|for|if|in|next|redo|rescue|retry|return|then|unless|until|when|while)\>/ {
+            yield keyword.control;
+        } else if /def\s+\w+\.(\w+[!?=]?)/ {
+            // Singleton method, as in `def self.foo`.
+            yield keyword.other;
+            yield $1 as method;
+        } else if /def\s+(\w+[!?=]?)/ {
+            yield keyword.other;
+            yield $1 as method;
+        } else if /(?:BEGIN|END|__ENCODING__|__FILE__|__LINE__|alias|and|class|defined\?|def|module|not|or|self|super|undef|yield)\>/ {
+            yield keyword.other;
+        } else if /(?:true|false|nil)\>/ {
+            yield constant.language;
+        } else if /(?i:-?(?:0x[\da-f_]+|0b[01_]+|0o[0-7_]+|[\d_]+\.[\d_]+(?:e[+-]?[\d_]+)?|[\d_]+(?:e[+-]?[\d_]+)?)r?i?)/ {
+            // Floats need digits on both sides of the dot, so that `1..2` and
+            // `1.upto(2)` don't swallow the dot.
+            if /\w+/ {
+                // Invalid numeric literal
+            } else {
+                yield constant.numeric;
+            }
+        } else if /(?:@{1,2}|\$)[A-Za-z_]\w*/ {
+            yield variable;
+        } else if /::/ {
+            // Scope resolution, so that `Foo::Bar` isn't mistaken for a symbol.
+        } else if /:[A-Za-z_]\w*[!?=]?/ {
+            yield constant.language;
+        } else if /[A-Z]\w*/ {
+            yield storage.type;
+        } 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;
+    }
+}