IMSA can refer to:
- Illinois Mathematics and Science Academy, a residential magnet school located in Aurora, Illinois
- IMSA Performance, a French sports car racing team
- International Management Systems Association, original name of the International Project Management Association (IPMA)
- International Mind Sports Association, an association formed by the international federations of several intellectual games
- International Motor Sports Association and its namesake IMSA auto racing series headquartered in Braselton, Georgia.
- International Municipal Signal Association, an association covering standards, certification, and training in areas of Fire Alarms, Highway Signs and Markings, Traffic Signals, and Roadway Lighting