Research on the development of self-regulation has focused primarily on the roles of maternal behavior and attention, but cognitive understanding of the self is also likely to contribute, as is exposure to maternal depression. In this study toddlers' understanding of self-as-object and understanding of agency were assessed behaviorally at both 20 and 27 months (N = 100). Maternal warmth during interactions was also observed at both ages. Half of the toddlers had been exposed to maternal depression. At 34 months toddlers' self-regulation was assessed behaviorally. As expected, toddlers' early understanding of the self (both self-as-object and agency) as well as maternal warmth predicted self-regulation later in toddlerhood. Maternal depression, however, was not associated with self-regulation. These findings provide empirical support for the theoretical construct of the self-system and suggest that early cognitive understanding of the self enables toddlers to better regulate their behavior. (Contains 4 tables and 1 figure.)