The impact of residential programs on the lives of severely-profoundly retarded adults will be studied prospectively for 2 1/2 years. The major goal is to identify important social and non-social variables that influence the ongoing behavior of this population. The significance relates to designing more optimal residential programs based on scientific data about basic environmental-behavior relationships. The primary methodology is direct behavioral observations of residents and staff in both living and training settings. Supplemental data include standardized assessment of skill levels, data about staff and family attitudes, and physical health. Baseline data will be collected for six months on the entire population (191) currently residing in a traditional institution--a large, isolated facility with 30-50 bed wards, limited staffing, and minimal programming for the low-level group. After baseline, all residents will move to new 14-bed living units with enriched staffing and training. Half the units (6 units, 84 residents) will comprise a pilot program to serve this population in residential neighborhoods with specialized community-based training; the other half will be situated on institutional grounds. Residents will be assigned on a random stratified basis either to a new institutional unit or to a specialized unit in a residential neighborhood. Follow-up data will be collected for two years. Detailed description of these new environments, as well as of the ongoing behavior of residents and staff, will permit assessment of the variable hypothesized to be critical determinants of behavioral change. These include: (1) social grouping, (2) specialized training, (3) opportunity to interact with outsiders, (4) diversity of resources, (5) preparation of residents and staff for change, and (6) biological factors. Behavioral changes are hypothesized to be maintained only to the degree that the environment supports or requires these behaviors for adaptation.