This paper describes an automatic roll mode control system for ground vehicles. The primary objective of the so-called “active suspension system” is to maintain a coordinated vehicle banking attitude during cornering and steering through traffic. Efforts were also made to render the vehicle insensitive to the undulation of the road surface, wind gusts, and other disturbance inputs. Emphasis was placed upon the development of design logic in the application of control system concepts to a physical system. Realization of the active suspension concept was achieved by parameter optimization of a simplified system on the analog computer and the design and construction of an experimental vehicle. Laboratory and road tests of the physical system confirmed the feasibility of the active suspension concept and brought to focus additional design considerations such as vehicle elastic mode and the effects of man vehicle coupling. For the road tests, a manual bias was incorporated in the automatic roll control loop to improve the transient response of the system, and the resultant man-machine multiloop interaction was investigated.