A number of studies have found that primary control declines in old age and is lower in Asian countries, while secondary control increases in old age and is higher in Asian countries. We examined whether these patterns may be due to the mediating influence of interdependence. In a sample of 557 young and old adults in Japan and the United States, primary and secondary control, age, and interdependence were measured. We found that interdependence mediates the influence of: (1) culture on secondary control; and (2) age on both primary and secondary control. Findings suggest that interdependence is an important factor that should be considered in trying to understand the determinants of control cross-culturally and developmentally.