Adaptive seating devices (ASDs) are used in the treatment of children with multiple handicaps. This longitudinal study evaluated, through direct observation and parent-guardian assessment, the behavioral changes seen with the use of ASDs and programming. Nineteen individuals with multiple handicaps and developmental disabilities, aged 1 to 6 years, participated as subjects. Data were collected by a trained observer from eight on-site evaluations and from parent-guardian responses to a preequipment and postequipment questionnaire. Evaluations were made every six weeks, starting about three months before and ending about six months after receiving the seating devices. The activities observed were head control, controlled sitting posture, visual tracking, reach, and grasp. Rating scale data were analyzed using an analysis of variance and a Friedman's test. Other data were analyzed descriptively for frequencies and central tendencies. Sitting posture, head control, and grasp improved significantly. Parent perceptions of the equipment indicated that the chairs freed parents from the need to provide support for their children's activities of daily living, which enabled them to participate in other activities with the children and around the home.