In a study to assess young children's social interaction with peers, six male toddlers who were the only participants in a playgroup were observed in two situations: (1) a GROUP situation in which at least four of the boys were present and (2) a DYAD situation in which only two boys were present. Both types of observations were made at 16, 19, and 22 months. The videotaped observations were analyzed for three sets of issues: (1) the range of individual differences present in the boys' social behavior and interaction, (2) the consistency of individual performance across the two settings, and (3) the stability of individual rankings between 16 and 19 months and between 19 and 22 months. These analyses indicated a considerable intra-individual stability across time and situation in addition to considerable inter-individual variability. These results are discussed in light of the emphasis most of the recent infant peer studies have placed on normative descriptions. (Author/CM)