For one school year, the classroom and playground social behaviors of normally developing and developmentally delayed children were analyzed for the occurrence of interactions across gender, across race and ethnicity, and across developmental condition. The potential impact of teachers' nonsexist language, and encouragement of interaction among mainstreamed peers, were also examined. Use of an ethnographic case study approach revealed increasing acceptance of mainstreamed children by peers, as well as several patterns of gender-segregated play. Interaction data showed gender to be used more than race and ethnicity in playmate choices at both centers. More cross-gender friendships were observed at the center with a gender balanced staff. The most gender-segregated play at both centers was seen on the playground and during other gross motor play, followed in frequency by free choice times. During such times, girls were observed attempting to join boys in their play. Implications for early childhood programs and teachers are discussed, along with implications for early childhood programs and the role of techers in promoting children's acceptance of diversity. (Author/RH)