Self-regulation is essential for adaptive behavior in everyday contexts that become increasingly elaborated and complex through childhood and adolescence. Here, we review literature and discuss our own findings regarding the development of executive control (EC) skills that support gains in self-regulation over the preschool years. Children's accuracy on executive inhibitory control, working memory, and flexibility tasks increases dramatically between 3 and 4 years of age, paralleling both quantitative and qualitative changes in neural volume and connectivity. Levels of proficiency on these EC measures are strongly tied to children's sociofamilial backgrounds, and particularly to family financial resources that facilitate access to learning materials and supports. Moreover, our data indicate that children's level of performance on EC tasks administered during preschool mediates the relation of family financial resources to children's mathematical achievement in early kindergarten. Collectively, findings indicate that the acquisition of EC represents a critical developmental task of early childhood and provides a platform for wellbeing across academic and socioemotional domains.