In this study, we reanalyzed the Forbes et al. (2002) data set to examine the Minnesota Multiphasic Personality Inventory (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) as a differential predictor of change across posttraumatic stress disorder symptom clusters following treatment in 141 Vietnam veterans. A series of partial correlation and linear multivariate regression analyses, controlling for initial symptom severity, identified several scales predictive of symptom change. None of the MMPI-2 scales, however, emerged as predictors of change in reexperiencing symptoms. Social alienation and marital distress were the most potent predictors for avoidance symptoms. Anger, alcohol use, and hypomania were the most potent predictors for the hyperarousal symptoms. Of the personality disorders, borderline personality was the strongest predictor of change in the avoidance and hyperarousal clusters. Further replication of the findings of this article and those reported by Forbes et al. (2002) is required.