Rogers' protection motivation theory that, in a fear-producing situation, stresses cognitive processes rather than emotional ones and emphasizes coping with or avoiding aversive events rather than reducing unpleasant emotional states and Bandura's theory of self-efficacy, i.e., all processes of psychological change operate through the alteration of the individual's sense of mastery, are both consistent with an expectancy-value model. However, each theory appears to omit a key component of the other. When the two theories are combined, a comprehensive model emerges. To test this model's ability to influence and predict changes in behavioral intentions, a factorial experiment was designed to examine the preventive health behaviors of 153 college students. Results disclosed an interaction effect interpreted in terms of two decision-making strategies that individuals use when confronted with danger: precaution and hyperdefensiveness. The results also provided evidence for self-efficacy as a causal factor in behavior change; direct manipulation of self-efficacy expectancies produced corresponding changes in behavioral intentions. The findings provide strong support for the importance of self-efficacy expectancy as a fourth component of protection motivation theory. (Author/JAC)