The most sincere resolutions to exert willpower–to diet, stop smoking, control anger–too often turn into failed good intentions. Beginning decades ago with Mischel’s “marshmallow test” experiments on delay of gratification with preschoolers, this lecture unpacks the conditions that enable self-control, and the basic cognitive and brain mechanisms that underlie resistance to temptation and the regulation of emotions. Mischel examines the implications of these discoveries for mastering self-control in everyday life, public policy, and the conception of human nature.