Research bearing on the psychoneurotic and psychosomatic theories of obesity is reviewed. The extent to which obese persons have been found to be suffering from a mental disorder or to evidence either a distinctive pattern of personality features or a characteristic emotionality is examined. The published reports on the mental status of obese patients in mental health settings show that many of these persons suffer from a neurotic or characterological disturbance involving issues of nurturance, growth and dependence. Obese general medical and nutrition clinic patients have been found to be psychologically disturbed in some cases and free of disturbance in other cases. Controlled research shows that a large proportion of these patients are indistinguishable from normal, nonobese persons on a variety of psychological measures. Another large group of obese medical patients have been found to suffer from various mild mental disturbances. Research comparing the mental status of obese and nonobese persons not under any form of medical care (e.g., government and factory workers) provides compelling evidence that obese persons who are unselected with respect to physical health and psychiatric status function as well or better than comparable nonobese persons. Although the research does not support a psychology of obesity based on psychoneurotic or psychosomatic process, the role of other behavioral and social influences in energy consumption and weight regulation merits careful investigation.