<p>The way in which literacy is conceptualised has serious implications for how it is addressed in policies, how it is taught and learned within programmes, and how it is measured and researched. Drawing on contributions to this journal, the <i>International Review of Education (IRE)</i>, this article explores how the concept of adult literacy has evolved, reflecting trends and changes in perspectives over the past seven decades. While the understanding of literacy has become more nuanced over time, we can still observe tensions between more holistic, comprehensive and integrated approaches to literacy that reflect a humanistic perspective, and narrower interpretations that focus on meeting socioeconomic needs and tackling “learning crises”. This analysis of those trends and perspectives focuses in particular on an understanding of literacy as a lifelong and life-wide learning process, which has been part of literacy discourses at least since the 1970s, though it first emerged much earlier. This review focuses on three closely interrelated questions: (1) How has the evolving notion of literacy been shaped by the principle of lifelong learning?; (2) Which issues have hindered the application of the lifelong learning principle to literacy?; and (3) What role can “lifelong literacy” play in the agendas for sustainable development and the transformation of education?</p>