Three factorial experiments examined the persuasive effects of the noxiousness of threatened event, its probability of occurrence, and the efficacy of recommended protective measures. A total of 176 students participated in separate studies on the topics of cigarette smoking, driving safety, and venereal disease. The results disclosed that increments in the efficacy variable increased intentions to adopt the efficacy variable increased intentions to adopt the recommended practices. Interaction effects revealed that when the preventive practices were effective, increments in the noxiousness and probability variables facilitated attitude change; however, when the coping responses were the preventive practices were effective, increments in the noxiousness and probability either had no effect or a deleterious effect, respectively. These interaction effects were discussed in terms of a defensive avoidance hypothesis, the crucial component of which was an inability to ward off the danger. Furthermore, the effect of the emotion of fear upon intentions was found to be mediated by the cognitive appraisal of severity of the threat. Finally, similarities with and extensions of previous studies were reviewed.