This article reports results from five studies. Exploratory factor analysis was used to select indicators from the Psychological Inventory of Criminal Thinking Styles, Levenson Self-Report Psychopathy scales, and Personality Assessment Inventory-Antisocial Features Scale. The 10 indicators were subjected to confirmatory factor analysis, the results of which show that the two-dimensional model (proactive, reactive) achieves significantly better fit than a general one-factor model and a two-factor social learning model (criminal thinking, antisocial behavior) with 521 medium-security and 116 maximum-security inmates. The construct validity of the two-dimensional model is confirmed in a path analysis pairing (a) proactive scales with positive outcome expectancies for crime and (b) reactive scales with hostile attribution biases. Implications for a unified theory of aggression and criminality are discussed.