The effects of same- versus mixed-age and sex dyad composition on the negotiating and general social interaction behaviors of preschool-age children were investigated. Subjects were 32 male and 32 female children who ranged from 3 to 5 years of age. A subject matching procedure produced 10 groups of dyads that varied systematically in age and sex composition. Dyadic behaviors of individual pairs were videotaped in an experimental room which was structured to elicit negotiating behaviors. Trained judges (n = 2) scored the videotapes by using a profile of negotiating behaviors and a profile of general social interaction behaviors; judges agreed uon 93% and 95% of their ratings when employing the respective profiles;The results generally failed to support the predicted age and sex effects; however, substantively meaningful findings were obtained. Pairs of younger females displayed higher mean levels of Rejecting behaviors than did pairs of older males, older females, or younger males. These dyads also evinced positive linear trends across time in judged Conceding behaviors, a pattern not holding for pairs of older males, older females, or younger males. Similar linear trends were found in judged Compromising behaviors in dyads containing female, as opposed to male, subjects. Finally, whereas dyads including either older subjects or mixed-age members increased in observed rates of task-oriented behaviors across time, pairs comprised of either younger subjects or of mixed-sex members showed the opposite trend. The results were discussed in light of relevant theory and of past research.