The purpose of this essay is to delineate the conceptual framework for psychiatry as an integrated and integrative science that unites the mental and the physical. Four basic philosophical perspectives concerning the relationship between mind and body are introduced. The biopsychosocial model, at this time the preeminent model in medical science that addresses this relationship, is examined and found to be flawed. Mental-physical identity theory is presented as the most valid philosophical approach to understanding the relationship between mind and body. Organic unity theory is then proposed as a synthesis of the biopsychosocial model and mental-physical identity theory in which the difficulties of the biopsychosocial model are resolved. Finally, some implications of organic unity theory for psychiatry are considered. 1) The conventional dichotomy between physical (organic) and mental (functional) is linguistic/conceptual rather than inherent in nature, and all events and processes involved in the etiology, pathogenesis, symptomatic manifestation, and treatment of psychiatric disorders are simultaneously biological and psychological. 2) Neuroscience requires new conceptual models to comprehend the integrated and emergent physiological processes to which psychological phenomena correspond. 3) Introspective awareness provides data that are valid for scientific inquiry and is the most direct method of knowing psychophysical events. 4) Energy currently being expended in disputes between biological and psychological psychiatry would be more productively invested in attempting to formulate the conditions under which each approach is maximally effective.Abstract Teaser