Previous studies have identified the MMPI-based Cook and Medley hostility scale (Ho) as a predictor of health outcomes. To achieve a better understanding of the construct measured by this scale, Ho items were classified on an a priori basis. Six subsets were identified: Cynicism, Hostile Attributions, Hostile Affect, Aggressive Responding, Social Avoidance, and Other. Study 1 examined the correlations of these subsets with scales of the NEO Personality Inventory in two samples of undergraduates. Good convergent and discriminant validity were demonstrated, but there was some evidence that items in the Social Avoidance and Other categories reflect constructs other than hostility. Study 2 examined the ability of the Ho scale and the item subsets to predict the 1985 survival of 118 lawyers who had completed the MMPI in 1956 and 1957. As in previous studies, those with high scores had poorer survival (chi 2 = 6.37, p = 0.012). Unlike previous studies, the relation between Ho scores and survival was linear. Cynicism, Hostile Affect, and Aggressive Responding subsets were related to survival, whereas the other subsets were not. The sum of the three predictive subsets, with a chi 2 of 9.45 (p = 0.002), was a better predictor than the full Ho scale, suggesting that it may be possible to refine the scale and achieve an even more effective measure of those aspects of hostility that are deleterious to health.