House, office, and in-hospital care under the Health Insurance Plan is provided to 550,000 persons by physicians who work almost exclusively in groups. The 32 groups operate medical centers in which more than 10 million dollars have been invested. Qualifications of group physicians are determined by a medical control board, and professional education programs for group members are provided. The quality of surgical, medical, obstetric-gynecologic, pediatric, laboratory, and x-ray services has been thoroughly evaluated, and the other departments are currently under review by specialists outside of the plan. Each medical group receives equal annual capitation for each insured person selecting that group, and each group operates its own plan of paying its distributable income to physician members. The accumulation of experience is enabling the organization to move steadily in the direction of comprehensive medical care of high quality.