Effortful control (EC) is an important developmental construct, associated with socioemotional growth, academic performance, and psychopathology. EC is defined as the ability to execute goal-directed behavior to inhibit or delay a prepotent response in favor of a subdominant response. Extant research indicates that EC may be multidimensional. Confirmatory factor analysis with a sample of 234 preschoolers was used to determine if tasks designed to measure EC were best described by hot (affectively salient) and cool (affectively neutral) dimensions or by a single factor. Analyses revealed that EC is best described by a single factor, even when variance associated with children's language skills was removed. This EC factor was strongly related to measures of academic performance and significantly less related to measures of socioemotional development. (Contains 5 tables.)