Contemporary sociological research has expanded knowledge about how the label of mental illness affects individuals and about how patients' and psychiatrists' social characteristics affect the assessment and treatment of mental disorders. The authors review the recent sociological research dealing with the effect of extrapsychiatric factors such as social class, race, gender, marital status, and age on the development, diagnosis, and treatment of mental illness. They also examine sociological studies of the social role of the state hospital, the consequences of deinstitutionalization for chronic mentally ill patients, and the relationship of mental illness and homelessness. Studies that examine the social aspects of psychiatric practice, including the objectivity of psychiatric diagnosis, are also reviewed.