Two groups of severely mentally handicapped people with behavioral disturbances were relocated within an institution from old to new group homes. This longitudinal study aimed at discovering the effects of (elements of) the new environment on individual and group behavior. Dependent variables were adaptive and maladaptive behavior, social interaction, and the use of (elements) of the physical environment. Special attention was paid to the possible uncovering of seperate effects of various independent variables, including the physical environment, treatment conditions, the group atmosphere and group and staff characteristics, and the complex interplay between these factors. The poster presentation will focus on the methodological issues in such a study, the design and instruments chosen, the results that were achieved and the recommendations that follow for the design of homes for similar groups.