Physical inactivity is responsible for major health and economic costs in the United States. Despite widespread recognition of the scope and importance of the problem of physical inactivity, only modest progress has been made in improving overall physical activity in the U.S. population. This paper applies a combined economic and public health perspective to better understand physical activity behavior and to guide a search for promising new economically oriented interventions to increase physical activity at the population level. This perspective is operationalized as the SLOTH model-a time-budget model incorporating Sleep, Leisure, Occupation, Transportation, and Home-based activities. Key economic forces that may influence individuals' choices about utilization of time and physical activity are identified. Potential interventions are proposed in response to each of the important forces and are evaluated on four criteria: (1) economic efficiency, (2) equity, (3) effectiveness, and (4) feasibility. The SLOTH model provides guidance regarding interventions that might increase physical activity in each of the four nonsleep domains. Economic intervention strategies are proposed and compared to economic and public health criteria. The results provide a starting point for selecting and evaluating potentially effective and feasible economic interventions that might be implemented as part of a larger effort to address the health crisis of inactive lifestyles and obesity.