This study explored the factor structure and developmental trajectory of effortful control (EC), its relations with child adjustment, and the moderating role of age and gender in 75 4- to 6-year-old children at risk for psychopathology. Confirmatory factor analyses revealed two subcomponents of effortful control: Suppress/Initiate (the ability to inhibit a dominant response while initiating a new response) and Motor Control (inhibiting fine and gross motor activity). EC performance improved with age, and both subcomponents were associated with greater social competence at all ages. Associations with internalizing problems were moderated by child age such that greater EC was linked to fewer problems at age 4 but did not relate to problems at ages 5 or 6.