The need for adult education and training (AET) is substantial, as labour markets require advanced skills. We used data from the Programme for the International Assessment of Adult Competencies (PIAAC) for Canada, the Netherlands, Norway, Sweden, and the United States (U.S.) to compare participation in AET by high- and low-skilled adults. Additionally, key informant interviews and document reviews were conducted. We found (a) low-skilled adults are less likely to participate in AET; (b) participation in AET is highest among the working population; and (c) non-formal education is often more acceptable to low-skilled adults. [This paper was published in: "Proceedings of Adult Education in Global Times: An International Research Conference," 2021, pp. 610-613.]