Self-regulation is a key construct in children's healthy and adaptive development. In this chapter, the authors situate self-regulation in a theoretical context that describes its underlying components that are most important for early school success: flexible attention, working memory, and inhibitory control. The authors review evidence that supports substantive links between these aspects of self-regulation and academic achievement in young children. They also discuss methodological challenges in reliably and validly assessing these skills (involving measures that are biased, are not applicable across broad age ranges, or triangulated) and describe some recent advances in measures of self-regulation (involving the NIH Toolbox or the Head-Toes-Knees-Shoulders assessment) that are reliable, ecologically valid, and predictive of children's school achievement.