CASR may stand for:
- State highways in California, the highways in the US state of California
- Centre for Automotive Safety Research, the road safety research centre based in the University of Adelaide
- Calcium-sensing receptor
- Civil Aviation Safety Regulation, which is set forth by the Civil Aviation Safety Authority, an Australian federal agency responsible for the regulation of private and commercial flight.
- Anarchic Cell For Revolutionary Solidarity, an anarchist urban guerilla group in Bolivia