The association between performance on health literacy measures and health outcomes is well established. The next step is to understand the processes through which health literacy affects health. This review introduces a framework drawing on ideas from health psychology and proposing that associations between health literacy and health outcomes could be mediated by a range of health actions involving access and use of health care, patient-provider interactions, and the management of health and illness. The framework outlines routes through which health literacy might affect either health actions themselves or the motivational and volitional determinants that have been identified in social cognition models. The implications of the framework for future research and intervention strategies are discussed. (Contains 2 figures.)