LEITER, MICHAEL P. A Study of Reciprocity in Preschool Play Groups. CHILD DEVELOPMENT, 1977, 48, 1288-1295. Child-child interactions were observed in 2 preschools during free-play time and were recorded in terms of social initiations and responses. The degree of reciprocity in the quantity and quality of overall initiations as well as among the various initiation/response dyads was analyzed. Friendly initiations were associated with more frequent agree responses, demanding initiations with more frequent coercive responses, and whiny initiations with ignore responses. There is evidence that the frequency with which an initiation mode is employed is associated with its efficacy in eliciting agree responses. In addition to the reciprocal patterns, evidence of complementarity in the demanding initiation mode was found. These findings are presented as a step toward a functional analysis of the reciprocal and complementary social interactions of preschool children.