We evaluated the convergent and discriminant validity of the Psychological Inventory of Criminal Thinking Styles (PICTS; Walters, 1995) in a group of 199 maximum security prisoners. As anticipated, the PICTS Confusion scale correlated with the Personality Assessment Inventory (PAI; Morey, 1991) Negative Impression scale, whereas the PICTS Defensiveness scale paralleled the PAI Positive Impression scale. Also as predicted, a greater portion of the PICTS thinking style scales correlated with the PAI Antisocial Features scale than correlated with the PAI Somatic Complaints, Anxiety, Depression, Mania, Paranoia, and Schizophrenia scales. When the PICTS composite scales were converged onto behavioral indexes, modest statistically significant relationships surfaced between the PICTS Reactive scale and a record of disciplinary infractions and between the PICTS Proactive scale and program completion.