Self-regulation, or the ability to control one's actions and responses, is essential for healthy development across varied contexts. Self-regulation comes in several forms, including emotional, behavioral, and cognitive. The present study sought to examine whether individual differences in one form of self-regulation was related to children's regulation in another domain. In addition, we explored whether different forms of self-regulation were similar in their contribution to preschoolers' understanding of false belief. Findings revealed concurrent relations among emotional, behavioral, and cognitive self-regulation. When measures of children's self-regulation were related to their performance on false belief tasks one year later, executive function predicted false belief understanding, while emotional and behavioral self-regulation did not contribute significantly to the model. These findings support the theory that self-regulation may consist of different interrelated types, including emotional, behavioral, and cognitive. In addition, the study provides important discriminant validity for the types of properties by which inhibitory control processes may be distinguished. (Contains 4 tables.)