Health literacy--the "ability to read, understand and use health information to make appropriate healthcare decisions"--was brought to national attention in April 2004 when the Institute of Medicine and the Agency for Healthcare Quality and Research published reports linking low health literacy with negative patient outcomes. Harvey Fineberg commented in the Institute of Medicine report, "Health Literacy, a Prescription to End Confusion": "Health literacy, enabling patients to understand and to act in their own interest remains a neglected final path to high quality healthcare." This article defines health literacy, describes the scope of the problem, identifies affected patient groups, and offers interventions to maximize patient understanding during the teaching process.