A ride control system for active damping of heave and pitch accelerations of surface effect ships (SES) is presented. It is demonstrated that distributed effects that are a result of spatially varying pressure in the air cushion result in significant vertical vibrations in low and moderate sea states. In order to achieve high quality human comfort and crew workability it is necessary to damp these vibrations using a control system which accounts for distributed effects owing to spatial pressure variations in the air cushion. To develop such a ride control system a mathematical model describing the motion of the craft in the vertical plane is derived. This mathematical model accounts for accelerations induced by both the dynamic uniform and the spatially varying air cushion pressure. Sensor and actuator placement is discussed, and the stability of the control system is analysed using the theory of passivity. The performance of the ride control system is shown by power spectra of the vertical accelerations and the pressure variations obtained from full-scale experiments with a 35 m SES.