Since the mid-1990s, developmental research has begun examining an important dimension of the family's emotional life previously neglected in studies of children and families-relational dynamics that take place at the level of the whole family group. A particular focus in this work has been on understanding the family's co-parenting dynamics. This work is in its infancy, and a number of important questions concerning co- parenting and family-level dynamics-particularly during the early years of family life-require systematic study. This project addresses four such questions: (1) Can parents' self-reports of their own co-parenting activities (behavior promoting family integrity, conflict disparaging the partner to the child) be tied to observational measures of related family processes? (2) What can be said about continuity versus change in family-level dynamics over time? (3) Are toddler self-regulation, internalizing and externalizing behavior linked to co-parenting dynamics before, and after, taking into account the child's temperament and the influence of dyadic relationship variables. (4) Is the association between marital distress and toddler adjustment mediated by co-parenting processes? 100 couples will participate in laboratory-based family interaction sessions with their child at 12 and 30 months, and be interviewed about their co-parenting relationship. At each time period, independent laboratory assessments will examine (a) each parent-child relationship; (b) the marital relationship; (c) interactions taking place at the level of the whole family group; and (d) child temperament. Toddler self- regulation, internalizing and externalizing behavior will be assessed at 30 months. Regression and MANOVA procedures will examine continuity and change in co-parenting and family-level dynamics form infancy to toddlerhood. Regression analyses will examine whether co-parental conflict, family cohesion, and discrepancies in engagement contribute uniquely to the prediction of toddler adaptation, beyond contributions of temperament and dyadic relationship properties. Latent variable path analysis with partial least squares examination procedures will examine direct (marriage-to-child) versus indirect (marriage-family-child) links.