Identifying effective policy interventions for adults with low literacy and numeracy skills has become increasingly important. The PIAAC Survey of Adult Skills has revealed that a considerable number of adults in OECD countries possess only limited literacy and numeracy skills, and governments now recognise the need to up-skill low-skilled adults in order to maintain national prosperity, especially in the context of structural changes and projected population ageing. Against this background, this literature review examines the current evidence on policy interventions for adults with low literacy and numeracy skills to clarify which targeted policy levers could best enhance socio-economic returns. Despite progress in measuring adult skills and extensive literature describing practices used in adult literacy and numeracy programmes, there is little analysis of the effects of different interventions on learners. This literature review therefore attempts to bring together the analytical insights from research and practice to provide a broad picture of what has so far proven to motivate low-skilled adults to join and persist in literacy and numeracy learning. The paper shows that low basic skills levels of adults are a complex policy problem that has neither straightforward causes nor straightforward solutions and successful interventions are relatively uncommon. Tackling serious literacy and numeracy weaknesses is challenging because the group of low-skilled adults is diverse and requires different, well-targeted interventions. But there is now an emerging body of evidence on the approaches to teaching and learning that can make life-changing differences to adults in need. The paper identifies formative assessment, e-learning, and contextualisation and embedding (especially in the workplace and family context) as effective approaches to basic skills teaching. The central challenge is to put the evidence to work.