The present study examined how variations in experiences salient to immigrant families are related to children's peer play and peer relationships in Head Start classrooms and explored the dynamics of peer interactions and relationships in classrooms with predominately children of immigrant families and with varying degrees of ethnic diversity. Subjects were 246 Head Start preschool children and their primary teachers. Almost all (91%) children came from families with foreign-born parents. Of those foreign-born parents, 35% were Latino, 44% Chinese, and 15% Vietnamese. Children with parents who reported getting together with other parents during non-school hours were more popular with their peers than children with parents who did not. The extent to which parents know other parents at the child's preschool was positively associated with the amount of time children spent in complex level play. Although children did not show a preference for same-ethnic peers as friends or play partners, same-ethnic dyads as opposed to cross-ethnic dyads played together more frequently and engaged in more complex play. Gender segregation in children's choice of friends and play partners continues to be more salient than racial segregation. Children who were popular with peers and/or had more friends were more likely to be rated by teachers as prosocial with peers and less likely to be rated as aggressive, asocial, hyperactive, or excluded by peers. Children were more popular in classrooms with more ethnic diversity. (author abstract)