Internationally, the field of adult literacy is a site of struggle. On the one hand, most agree that literacy is a critical resource for negotiating one's social and economic life. On the other, public funding for adult literacy programmes is not generally guaranteed or adequate. However, for individuals and communities with limited literacy, issues such as widespread food insecurity, lack of safe water, ongoing conflict and war, historical and systemic legacies of colonisation and the ascendancy of far-right political parties increase their vulnerabilities. While many grassroots adult education programmes aim to address these challenges at the local level, these efforts often struggle to be recognised in policies that provide sustained funding. We analyse this dynamic through the lens of a four-level model of mega-, macro-, meso- and micro-level policy, advocacy, and practice activities in Australia, Brazil, India and South Africa. Doing this is particularly salient against the backdrop of the United Nations' Sustainable Development Goal 4 which has set targets for adult literacy. The model renders visible barriers that impede progress towards meeting SDG 4 targets in each of these countries. The model also enables comparison across the case descriptions that could be instructive for international as well as local debates about strengthening adult literacy provision.