Continuity of medical care is conceived as the extent to which services are received as part of a coordinated and uninterrupted succession of events consistent with the medical care needs of patients. Two operational measures are proposed, based on the Gini and CON indices of concentration. Examples of their application are provided using the 1970 CHAS-NORC national study of health services utilization. The validity of the proposed measures is assessed in a preliminary fashion, and some commonly held assumptions about the relationship between access, quality, and continuity of care are challenged. Advantages of the proposed measures include their ability to summarize a distribution, the availability of data for construction, the relative ease of computation and interpretation, and their sensitivity to organizational changes in the delivery of health services.