Self-affirmation, a process by which individuals reflect on cherished personal values is a potent means of augmenting the effectiveness of threatening health communications. Individuals tend to be defensive against information suggesting their behavior puts them at risk for disease or negative health. Previous evidence suggests that self-affirmation may reduce defensiveness to threatening health information, increasing openness to the message and resulting in increased disease risk perceptions, disease-related worry, intentions to engage in preventive behavior, and actual behavioral change. Understanding the mechanisms that explain these robust effects would yield evidence important for dissemination, including ways to refine self-affirmation interventions and make them more potent, which could change the ways that public health messages are constructed. Thus, we aim to elucidate potential mechanisms underlying the effectiveness of self-affirmation, including self-activation, general affirmation, and domain-specific affirmation. In study 1, female human subjects will be randomly assigned to one of eight affirmation or self-activation conditions. Following the affirmation or activation task, subjects will read about the documented link between alcohol and breast cancer. Finally, they will be asked a series of questions about their intentions to reduce drinking, their perceived risk of breast cancer, and their worry about breast cancer. Study 2 will replicate study 1, but in a different behavioral domain (fruit and vegetable consumption) and a different sample (both males and females who do not meet fruit and vegetable recommendations. Study 3 will extend Studies 1 and 2 by examining whether the most effective self-affirmations identified in these studies produce short-term increases in fruit and vegetable consumption. Drawing on previous research, we hypothesize that these inductions will be effective to the degree that they involve a self-affirmation, but will not be effective if they involve only other-affirmation or self-activation.