Five- to seven-year-old second-born children from white, middle-class, intact families were the subjects for this study. Older siblings served as role model for each child, and the parent surrogate models were selected from a pool and trained to act as the child's real parent. The imitation task emphasized verbal, postural, and motor responses of two models playing a game. One point was assigned to the subject for each imitative response which could be attributed to the performance of either the parent surrogate or the sibling model. Overall, the assumed sibling effect in cross-sex dyads was more evident for second-born females than males. Second-borns in same-sex dyads appeared to imitate the same-sex parent more than their older sibling; the converse effect occurred for second-borns in cross-sex dyads. Indications were that in two-child families, children of the same sex compete for parental attention. In summary, imitation behavior of second-borns appears to be influenced by dyad composition and family configuration. This study raises the question of what types of family interaction patterns influence behavior of second-borns. (Author/PC)