Health literacy as a discrete form of literacy is becoming increasingly important for social, economic and health development. The positive and multiplier effects of education and general literacy on population health, particularly women's health, are well known and researched. However, a closer analysis of the current HIV/AIDS epidemics, especially in Africa, indicates a complex interface between general literacy and health literacy. While general literacy is an important determinant of health, it is not sufficient to address the major health challenges facing developing and developed societies. As a contribution to the health literacy forum in Health Promotion International, this paper reviews concepts and definitions of literacy and health literacy, and raises conceptual, measurement and strategic challenges. It proposes to develop a set of indicators to quantify health literacy using the experience gained in national literacy surveys around the world. A health literacy index could become an important composite measure of the outcome of health promotion and prevention activities, could document the health competence and capabilities of the population of a given country, community or group and relate it to a set of health, social and economic outcomes.