The paper summarizes recent data on the retention and non-completion patterns of adult students, especially those over the age of 25 who have had a gap since completing full-time education. While data on further and higher education suggest that older learners are less likely than younger ones to complete longer, qualification-bearing programmes, central statistics do not distinguish between students in their early-to-mid 20s, many of whom still have much in common with those in their late teens, and those in their 30s, 40s and 50s whose lifestyles, learning goals and aspirations are often qualitatively different. The section on retention data is followed by a summary of the reasons for not completing courses commonly cited by adults learning in conventional education settings, and reflection on whether these are significantly different from those cited by younger students and students in open or distance learning programmes. The paper ends with a summary of the kind of factors that might increase adult retention rates in both kinds of learning programme. For the purposes of this paper, "adults" are defined as those over the age of 25 who have had a gap since completing full-time education.