In this article, Cybele Raver and Clancy Blair explore a group of cognitive processes called executive function (EF)--including the flexible control of attention, the ability to hold information through working memory, and the ability to maintain inhibitory control. EF processes are crucial for young children's learning. On the one hand, they can help students control their anxiety when they face challenging academic tasks. On the other, these same processes can be undermined when children experience chronically stressful situations--for example, poverty, homelessness, and neighborhood crime. Such adverse early experiences interfere with children's development of EF, hampering their ability to manage challenging situations. Through both behavioral examples and empirical evidence, Raver and Blair illustrate how children's cognitive development is intertwined with EF. They show how children's regulation of higher-order thinking is related to the regulation of emotion--in both top-down and bottom-up fashion--and they review research on early brain development, EF and emotion regulation, and children's academic performance. They also examine the efficacy of educational interventions that target EF and of integrated interventions that target both emotional and cognitive regulation. What does our understanding of EF imply for policy in pre-K-3 education? First, write Raver and Blair, to help young children learn, school districts need data not only on their academic readiness but also on key dimensions of EF. Second, we already have interventions that can at least partially close the gap in neurocognitive function and academic achievement between children who face multiple types of adversity and those who don't. In the long run, though, they argue, the best way to help these children is to invest in programs that reduce their exposure to chronic severe stress.