New parenthood calls for husbands and wives to work together, coordinate attitudes and beliefs, and to respect, and perhaps negotiate between, one another's unique ideas about raising children. The contribution of such marital processes to parent-child relationships is highlighted by more than 2 decades of research examining the interrelation of marriage, parenting, and child development (Gable, Belsky, & Crnic, 1992). Presently, it is recognized that happy marriages are frequently associated with supportive parenting and with favorable child outcomes (e.g., Belsky, Youngblade, Rovine, & Volling, 1991; Howes & Markman, 1989, 1991) and that troubled marriages are often related to less effective parenting and problematic child behavior (e.g., Jouriles, Murphy, Farris, Smith, Richters, & Waters, 1991; Kerig, Cowan, & Cowan, 1993). Because associations between marriage, parenting, and child development are not uniform and are often modest (Reid & Crisafulli, 1990), the need to move beyond global assessments of marital quality and to investigate marital processes from a more differentiated perspective is now widely acknowledged (Jouriles, Farris, McDonald, 1991; Jouriles, Murphy, et al., 1991; Vuchinich, Vuchinich, & Wood, 1993). Recent efforts to specify which aspects of the marital relationship impede parenting and place children at risk repeatedly highlight overt inter spousal arguments (Gottman & Katz, 1989; Holden & Ritchie, 1991; Jenkins & Smith, 1991; Jouriles, Murphy, & O'Leary, 1989; Katz & Gottman, 1993). Cummings and his colleagues have reported that characteristics of interparental anger (e.g., frequency, mode, topic of conflict) and its resolution (e.g., the silent treatment, compromise) are linked with child well-being (e.g., Cummings, Ballard, El-Sheikh, & Lake, 1991; Cummings & Davies, 1992; Cummings, Vogel, Cummings, & El-Sheikh, 1989; Cummings, Zahn-Waxler, Radke-Yarrow, 1981). Furthermore, in a study that considered disputes about parenting as a dimension of marital quality, Jouriles, Murphy, et: al. (1991) found that marriages characterized by high levels of conflict about childrearing were more strongly and positively associated with boys' behavior problems than were self-reports of general, non-child-related conflicts. In light of such findings, the main goal of this study is to widen the window on the marital relationship and describe how spouses function as coparents. Family systems and psychoanalytic theorists have characterized the coparenting relationship as the extent to which husbands and wives function as partners or adversaries in their parenting roles (P. Minuchin, 1985; S. Minuchin, 1974; Weissman & Cohen, 1985). Despite the apparent significance of these ideas, few studies of coparenting processes have been conducted (for exceptions, see Buchanan, Maccoby, & Dornbusch, 1991; Floyd & Zmich, 1991; Frank, Jacobson, Hole, Justkowski, & Huych, 1986; Maccoby, Depner, & Mnookin, 1990). Some researchers have indirectly estimated coparenting by comparing mothers' and fathers' childrearing attitudes and beliefs (e.g., Block, 1965; Block, Block, & Morrison, 1981; Vaughn, Block, & Block, 1988); still others have interviewed parents about their perceptions of their partner as a supportive coparent (Frank et al., 1986). Although this research adds to the understanding of parental alliances, it is striking that a naturalistic, behavioral data base about coparenting has not emerged. Thus, the purpose of this investigation is to characterize the nature of coparenting processes using home-based observations of family interaction. Toward this end, a behavior-based classification system designed expressly for measuring naturally occurring coparenting events will be detailed, and evidence pertaining to stability and change in the frequency and style of coparenting over a 6-month period during the 2nd year of life will be presented. …