The importance of effective planning strategies for the location of primary medical services for the independently living elderly increases as their absolute number and proportion in the general population increases. Current spatial planning strategies focus on providing services in centralized locations or decentralized at the level of the somewhat problematic residential "neighborhood" or catchment area. An alternative or supplemental strategy based on the actual use of community space by the elderly is presented in this article. Aggregate activity spaces are identified and illustrated using activity location data obtained for a sample of elderly urban residents. Subsequently, the aggregate spaces are used as a basis for suggesting the location of ambulatory care facilities. It is believed that the aggregate activity space represents a dynamic and more functional approach to spatial planning strategies than current approaches and, therefore, that it can be used more effectively to locate services for the elderly.