Research using a categorical-polythetic classification system for mental illness has raised concern regarding the validity of categorical classification systems. Recent efforts suggest psychopathology is better understood from a dimensional framework, though there has been varying evidence of a somatization factor. The current investigation seeks to produce and validate a dimensional model of psychopathology, with a particular emphasis on the placement of somatization, across three nonoverlapping medical samples. Using a bariatric surgery seeking sample (n = 1,268), a spine surgery/spinal cord stimulator seeking sample (n = 1,711), and a chronic pain treatment seeking sample (n = 1,388), a dimensional model of psychopathology was replicated across all three samples using a dimensional measure of psychopathology (the Minnesota Multiphasic Personality Inventory-2-Restructured Form [MMPI-2-RF]). Clear evidence of a separate somatization factor was found in addition to broad internalizing, externalizing, and social detachment factors. Constructs assessable with the model yielded good convergent and discriminant validity coefficients with external criteria, and further supported the presence of a higher-order somatization construct. (PsycINFO Database Record (c) 2019 APA, all rights reserved).