The social outcomes of two mainstreaming programs were compared for 24 first through third grade handicapped children. Ss were randomly assigned to one of two placements: a traditional resource room or an adaptive educational program. Placement differed in the amount of time students spent in an integrated setting, the instructional practices, and the opportunities for both instructional and social interactions. Observational data on classroom processes were analyzed to document the distinguishing characteristics of the social and academic environments in which the Ss were placed. Differences were then examined in relation to Ss' self repots of competence, friendship patterns, and peer acceptance. Results revealed that social outcomes varied markedly across the two programs. More positive trends were uncovered in the adaptive program where children were placed in the integrated setting on a full time basis, learning assignments were matched to ability levels, itinerant services were provided as much as possible within the classroom, and opportunities to interact with peers and form personal relationships were frequent. Handicapped Ss in the adaptive education program had higher self ratings of competence and received higher peer acceptance ratings than did handicapped Ss in the resource room program. (Author)