Though there has been a considerable expansion of interest in the health literacy concept worldwide, there has also been criticism that this concept has been poorly defined, that it stretches the idea of "literacy" to an indefensible extent and more specifically, that it adds little to the existing concerns and intervention approaches of the better established discipline of health promotion. This paper takes as a starting point the expanded model of health literacy advanced by Nutbeam (2000) and addresses these concerns by interrogating the concept of "critical health literacy" in order to draw conclusions about its utility for advancing the health of individuals and communities. The constituent domains of critical health literacy are identified; namely information appraisal, understanding the social determinants of health, and collective action, and as far as possible each are clearly delineated, with links to related concepts made explicit. The paper concludes that an appreciation of work undertaken in a range of different disciplines, such as media studies, medical sociology, and evidence-based medicine can enhance our understanding of the critical health literacy construct and help us understand its usefulness as a social asset which helps individuals towards a critical engagement with health information. There is some evidence that aspects of critical health literacy have indeed been found to be a resource for better health outcomes, but more research is needed in this area, both to develop quantitative and qualitative approaches to evaluating health literacy skills, and to offer convincing evidence that investment in programmes designed to enhance critical health literacy are worthwhile. Copyright © 2011 Elsevier Ltd. All rights reserved.