Current health care policy emphasizes improving health outcomes and the efficacy of health care delivery by supporting informed consumer choices. At the same time, health information often involves uncertainty, and many people may lack the skills and knowledge to process this information, manage their health and health care, and make informed choices. Innumeracy, an element of poor health literacy, is associated with the comprehension and use of important health information. We review this literature and examine what can be done to help less numerate people act more effectively and take charge of their health.