Health Literacy is a concept that is complex and dynamic, and takes into account how people access, understand and use health information and health care in everyday life and in medical situations. There is an increased recognition of the contextual nature of health literacy, and how risk factors across the social ecology can affect health literacy. When individuals can effectively access, understand, and use health-related information (i.e., have high health literacy) their short- and long-term health outcomes improve. Health professionals must also provide accessible, understandable, and meaningful information (i.e., at appropriate literacy levels) in order for people to use that information, navigate the health system, and better control their health outcomes. Thus, the purpose of this dissertation is to examine the gap between the health literacy demands of consumers and the provision of health information by health education and health care professionals. Enhancing health literacy may be an important step on the pathway to reducing health disparities. Health literacy plays an important role in health disparities either because a population may have poorer health literacy (e.g., low SES), or because a population has greater health care needs (e.g., older adults, people with disabilities) and thus greater demands to be health literate. This dissertation will focus on aspects of health literacy among high-risk populations including provider-patient communication and consumer health information seeking behaviors and add to the understanding of how the mismatch between health literacy demands of patients and consumers and the health information supply from providers and educators affects individuals with poor health literacy and great health needs.