Six personality measures used in health psychology; the NEO Five-Factor Inventory (NEO-FFI) criterion measures of stress, self-reported health status, and coping; and a measure of social desirability were administered to samples of college students and adult community volunteers ( N = 589) in a series of four confirmatory and exploratory factor analytic studies. The hypothesis that the six independently developed personality measures of ego-strength, hardiness, self-esteem, self-efficacy, optimism, and maladjustment would share common variance and that a hierarchical factor model with a single, higher-order Health Proneness factor loading two lower-order factors—Self-Confidence and Adjustment—would account for the covariance in these measures was tested against single and three-factor models and confirmed. The factor model was examined with respect to general personality as represented in the “Big Five” Model. Adjustment was related negatively to NEO-FFI Neuroticism and positively to NEO-FFI Conscientiousness and Agreeableness, whereas Self-Confidence was related to NEO-FFI Extraversion. None of these relationships is extensive, nor does any one account for more than 40% of the variance. Evidence of the validity of Self-Confidence and Adjustment was found in their moderate relationships to measures of stress, health status, and coping, and in their weak relationships to social desirability and negative affectivity.