A study of the effectiveness of preschoolers interpersonal interactions was conducted based upon a circumplex model of interpersonal behavior and the corollary complementarity hypothesis developed by Leary (1957) and Carson (1969) The interpersonal styles of 92 preschoolers' interpersonal interactions was rated in a naturalistic free-play environment These ratings were used to obtain status and affiliation scores for each child which, in turn, were the basis for assigning subjects a complementary or an anticom-plementary partner It was predicted and found that complementary pairs performed a difficult puzzle task more efficiently than did anticomplementary pairs The usefulness of the complementarity hypothesis and implications for its use in future research were discussed