Health care professionals have become increasingly interested in motivating individuals to comply with health recommendations. One approach to this issue has been to evaluate the impact of message framing on behavior change processes. Three types of framing are described: gain, loss and fear. Theoretical considerations from such theories as the Health Belief Model, Prospect Theory, and Protection Motivation reveal the significance of two dimensions, the perceived value and perceived threat of an outcome. The perceived value dimension focuses on the importance of defining messages on the basis of whether or not a valued outcome is acquired, and the perceived threat dimension stresses the importance of negative outcomes. Perceived value is critical to a manipulation of gain and loss framing, while perceived threat is critical to a manipulation of fear framing. The assumptions underlying the theories relevant to these distinctions are considered, followed by a review of the literature, and speculations about the possible mechanisms which may mediate framing effects.