The present study investigates the nature of positive engagement (an interpersonal style characterized by attentiveness, warmth, cooperation, and clear communication) in family interactions involving at least one adolescent. Approximately 400 families (mothers, fathers, and two siblings) were videotaped during brief conflict-resolution discussions that occurred on a yearly basis for 3 years. Coders rated the degree to which each family member was positively engaged with every other family member during the interactions. The social relations model was used to partition variation in positive-engagement behavior into family-level, individual-level, and dyad-level effects. Results demonstrated the importance of family norms and individual factors in determining the expression of positive-engagement behaviors in dyadic family relationships. Moreover, longitudinal analyses indicated that these effects are stable over a 3-year period. Finally, results highlighted the relative distinctiveness of the marital and sibling relationships, as well as the existence of reciprocity within these dyads.