Background Studies clearly indicate that parenting practices relate to child externalizing behaviors, although the mechanisms underlying this relation are less well understood. There has been limited evaluation of child routines and self-regulation in relation to these variables, and no known studies have evaluated all of these variables simultaneously. Objective This study examined child routines and self-regulation as serial mediators of the relations between positive and negative parenting practices (separately) and child externalizing problems among preschool children. Methods Participants included 146 maternal caregivers of preschool children who completed measures of their parenting practices and of their child's daily routines, self-regulation, and externalizing behaviors. Results Results demonstrated that both child routines and self-regulation are significant mechanisms through which negative and positive parenting practices relate to externalizing problems in preschoolers, although the temporal sequencing was only upheld with respect to negative parenting. Our findings offer preliminary evidence that child routines may play a critical role in self-regulation development among preschool children, which, in turn, is inversely associated with externalizing behaviors. Conclusion Although further study is needed, these findings suggest that child routines and self-regulation development may be key components to incorporate clinically and evaluate empirically among intervention programs designed to prevent early development of behavior problems in preschool children.