The relationship between literacy and health outcomes are well documented in adult medicine, yet specific causal pathways are not entirely clear. Despite an incomplete understanding of the problem, numerous interventions have already been implemented with variable success. Many of those who proposed earlier strategies assumed the problem to originate from reading difficulties only. Given the timely need for more effective interventions, it is of increasing importance to reconsider the meaning of health literacy to advance our conceptual understanding of the problem and how best to respond. One potentially effective approach might involve recognizing the known associations between a larger set of cognitive and psychosocial abilities with functional literacy skills. Here we review the current health literacy definition and literature and draw on relevant research from the fields of education, cognitive science, and psychology. In this framework, a research agenda is proposed that considers an individual's "health-learning capacity," which refers to the broad constellation of cognitive and psychosocial skills from which patients or family members must draw to effectively promote, protect, and manage their own or a child's health. This new, related concept will lead, ideally, to more effective ways of thinking about health literacy interventions, including the design of health-education materials, instructional strategies, and the delivery of health care services to support patients and families across the life span.