A nationwide study of practitioners in 24 medical and surgical specialties was conducted by the University of Southern California School of Medicine, Division of Research in Medical Education. In this second report of a series presenting findings for internal medicine, general internal medicine and 10 subspecialties of internal medicine are compared using a care classification scheme designed for the study. On the basis of characteristics of the individual patient encounter, this care classification scheme distinguishes several dimensions associated with the concept of primary care. Five empirically derived types of care rather than a simple “primary” or “non-primary” dichotomy are described, and the distributions of each type for the 11 subspecialties examined are noted. Types of care (according to the care classification) are examined by the time per patient, the complexity of physician services, the severity and chronicity of problems, and the degree of specialization associated with providing different types of care. Estimates of the number of annual encounters, and the number of annual encounters for three of the five types of care, with the proportion of each accounted for by each subspecialty, are given.