This paper describes a retrofit noise control study for existing, electric-powered transit cars currently operated by the New York City Transit Authority. The study focused on a test car considered to be representative of the fleet, that was outfitted with monitoring equipment and operated through a series of experiments. The dominant noise-producing components were determined and the important noise and vibration transmission paths located. Simple, easy-to-implement treatments that would reduce the noise levels to acceptable levels were recommended. Some of these recommendations included better side-door and end-door seals, increased floor mass, and quieted traction mooor fans.