The focus of this paper is adult literacy, and the impact this has on Aboriginal and Torres Strait Islander individual and community health. It directs attention to those Aboriginal and Torres Strait Islander young people and adults who have not benefited from the formal school education system, and who, as a consequence, have very low levels of basic English language literacy. Analysing data from a range of sources, I suggest that these people comprise as much as 35% of the Aboriginal and Torres Strait Islander adult population nationally, and a much bigger proportion in some communities and regions. Moreover, they are key to improving overall health outcomes in the population as a whole, because they are among the people most at risk. Drawing on research in countries of the global South over recent decades, the paper then suggests that one of the most effective ways to improve health outcomes and foster health development is through a popular mass adult literacy campaign. Popular education is not formal education, of the kind provided by schools, TAFEs and universities. It is "non-formal" education, provided on a mass scale, to people in marginalised and disadvantaged communities, as part of wider social and political movements for equality. The paper concludes that this is the most appropriate form of education to deal with the massive social and economic inequality at the heart of the social determinants of Indigenous health.