Theoretical models of mental health provide essential contributions to our understanding of psychopathology. The important role of theoretical models in predicting, classifying, and treating psychopathology is discussed. Further, a review of the evolution of theoretical models of mental health, from the early medical model to psychological and social models to a more comprehensive biopsychosocial model, is provided. Advantages of the biopsychosocial model are discussed along with its application to psychopathology, including schizophrenia and mood, anxiety, and eating disorders. Although complex, the biopsychosocial model is fundamental for the comprehensive conceptualization of psychological disorders and individualized treatment.