Abstract. Many have criticized the Diagnostic and Statistical Manual ofMental Disorders (DSM-IV), and few regard it as a vehicle of truth, yet its most serious limitation is that its frank operationism in defining manifest categories has distracted attention from theories about what is going on at the latent level. We sketch a Generalized Interpersonal Theory of Personality and Psychopathology and apply it to interpersonal aspects of depression to illustrate how structural individual differences combine with functional dynamic processes to cause interpersonal behavior and affect. Such a causal account relies on a realist ontology in which manifest diagnoses are only a means to learning about the latent distribution, whether categorical or dimensional. Comorbidity of DSM diagnoses suggests that dimensionality will be the rule, not the exception, with internalization and externalization describing common diagnoses.Key Words: Big Five, circumplex, complementarity, depression, Dimcat, expressed emotionThe fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 1994) virtually holds a monopoly on the classification of psychopathology. Nearly every textbook on abnormal psychology uses DSM classifications so that, as a consequence, professors will choose the book as a way to prepare their students for successful careers in the helping professions; researchers who study psychopathology know that they probably will not receive grant funding unless they define their terms according to the DSM nomenclature. Because of the extraordinary prominence of the DSM in clinical psychology, psychiatry, and related professions, careful attention to the DSM's philosophical and methodological underpinnings seems warranted.The present article is divided into four parts. The first section provides a clear understanding of how the current DSM has evolved from its predecessors. The second section distinguishes functionalism from structuralism and applies this distinction to the DSM. The third section expands on an Theory & Psychology