We examined the nature and directionality of associations between interparental discord and parenting practices in a sample of 227 mothers and fathers of kindergarten children over two measurement waves spaced 1 year apart. Cross-lagged models indicated that associations between interparental discord and maternal and paternal parenting practices (i.e., acceptance, discipline) were generally negligible with one exception: interparental discord at Time 1 predicted decreases in maternal acceptance from Time 1 to Time 2. However, consistent with the family systems conceptualization of the family as an open system, prospective associations among interparental and parent-child subsystems varied significantly as a function of parental depressive symptoms, interparental relationship insecurity, and child-rearing disagreements. The moderating role of adult characteristics commonly varied across the type of adult vulnerability (e.g., depressive symptoms, interparental relationship insecurity, child-rearing disagreements), dimension of parenting practices (e.g., maternal and paternal acceptance and inconsistent discipline), and the directionality of the paths between interparental and parent-child subsystems.