Angela Lee Duckworth is a full-time, tenure-track Assistant Professor of Psychology at the University of Pennsylvania. Her long-term career goal is to establish an interdisciplinary research program on self-control and other capacities that determine economic, social, and health outcomes across the life course. Dr. Duckworth seeks the support of a Mentored Research Scientist Development Award (K01) to develop skills and knowledge in two areas in which she has no formal training: economics and aging. It is well-established that cognitive ability (i.e., intelligence) is a powerful determinant of mortality, years of schooling, savings behavior, criminal behavior, employment, income, and other important outcomes. There is more recent evidence that personality traits predict the same outcomes, even when controlling for cognitive ability. As yet, research in economics and psychology has failed to specify which personality traits, above others, causally determine outcomes. Identifying the capacities that matter most for success is essential for policy and intervention. Further, it is essential to understand how these capacities develop across the life course and their susceptibility to intervention and investment. The proposed research examines self-control, the capacity to override impulses in order to act in one's best recognized interests. Research from criminology, sociology, psychopharmacology, psychiatry, personality psychology, and developmental psychology suggests that the capacity of self-control is crucial to successful functioning in every domain of life. Moreover, self-control is the closest conceptual analogue to the economic construct of time preference, the discount placed on future utility as a function of the delay to its consumption. Training in economics and aging will enable the applicant to accomplish the following specific research aims: (1) Develop a multi-dimensional measurement system linking self-control and time preference;(2) Establish the causal role of self-control and other capacities for economic, social, and health outcomes across the life course;and (3) Develop a model of the development of self-control across the life course. In prior research, the applicant has related self-control to academic achievement in youth. The proposed KOI significantly extends this work in terms of scope and methodological approach. Self-control enables people to do what they want and know they should do. The proposed didactic and research activities marry the approaches of economics and psychology to advance understanding of the causal role, life course development, and measurement of this crucial capacity.