The health belief model and protection motivation theory are two of the earliest formulated expectancy-value accounts of behavior change. Across nearly six decades, the importance of these accounts has persisted. Both models advocate that behavior change is a consequence of two important processes: threat appraisal comprising the extent to which an individual perceives personal susceptibility to a consequence, combined with the severity of that consequence, and coping appraisal comprising evaluations of the likely efficacy of a recommended action to reduce threat, expectations that taking that action will involve difficulties and psychological costs, and personal efficacy to achieve behavior change. Multiple studies support the predictive validity of the models and many interventions have been developed based on the theoretical principles provided. Behavior change based on these models requires careful consideration of behavior-specific cognitions and careful targeting of these cognitions. Moreover, behavior change interventions should target threat appraisal enhancement only in combination with detailed and extensive training or communication that targets efficacy to enact behavior change.