Recent studies of early socialization and child development have begun to contextualize early family influences more broadly than ever before. Yet, despite advances in family and child research over the past decade, most studies continue to examine dydadic subsystems of the larger family system rather than the full family context. With a few noteworthy exceptions, empirical support for the utility of whole-family analysis in child development research remains to be established. This sourcebook draws together diverse studies of whole-family dynamics to explore the potential of this paradigm for understanding individual variability in children's early social and emotional development. Several chapters underscore the significance of coparental processes--behaviors between adults that include and involve the child. Other chapters assess patterns of cohesion, emotion, coordination, and involvement among members of the family group. Though the studies reported in this sourcebook capture family-level processes in only one type of family--the two-parent family--they provide a knowledge base from which subsequent research on other family configurations can proceed. It is our hope that this sourcebook moves us one step closer to realizing the rich and nuanced perspectives inherent in the careful clinical observations and writings of family therapists who emphasize the relevance of the whole-family group for our safety, health, security, and reality. This is the 74th issue of the quarterly journal New Directions for Child Development.