The Space Shuttle Reaction Control System design requirements, regimes of operation, and physical characteristics are described to show how they influenced the subsystem design. An overall RCS description and discussion of several components including the thruster, propellant tank, AC propellant isolation valves, and burst disc pressure relief valve assembly are presented. The current status of the Forward Reaction Control System development tests at the NASA-White Sands Test Facility are discussed including test results and unique developments encountered as a part of the test program.