DEFD is an NIMH Funded Interdisciplinary Behavioral Science Center. The center is designed to understand executive function at three levels—the computational, the psychological, and the neurobiological—and integrate them to provide a unified theoretical perspective. To do so, each of DEFD’s projects investigates a particular aspect of executive function at all three levels. One of the center’s projects focuses on the representations supporting executive control and its development during childhood while another examines the effect of emotion on executive function. Other projects investigate executive function by means of analyzing molecular genetic analyses in concert with computational modeling to begin to specify in more detail how the dopamine (DA) system regulates three separable but correlated executive subcomponents—prepotent response inhibition, updating working memory, and set shifting. Another project utilizes a fMRI/ERP approach to test how well a temporal cascade model of cognitive control can explain facets of executive function, such as task switching. Lastly, we have a project that explores how PFC representations are shaped by the interaction between experience and the unique biological mechanisms of the PFC and associated brain areas in the basal ganglia and dopaminergic system. Only by integrating and synthesizing ideas and findings across these different levels of analysis will the field arrive at a fully adequate understanding of executive function.