This paper identifies important knowledge gaps in adult education and training (AET) in Canada and starts to explore strategies to fill these gaps. Following an introduction in English and French, each of the next three sections is comprised of a review of the current state of knowledge on three topics (outcomes of adult learning, motivations and barriers to adult learning, and informal learning) and a discussion of major knowledge gaps relevant to each. Section 2, on outcomes, argues that more must be known about outcomes in terms of overall benefits and costs if the adequacy of AET in Canada is to be judged. Section 3, on motivations and barriers, reports that key knowledge gaps include understanding reasons for participation and non-participation, and assessing whether individual decisions to participate or not are somehow unwarranted because they do not fully reflect associated costs and benefits. The section also argues that increasing knowledge of barriers to AET is a complementary strategy to estimating rates of return in the process of judging the adequacy of training levels in Canada and is essential in design of specific policy actions towards the pursuit of equity goals. Distribution considerations are addressed. Section 4 discusses issues related to informal learning and questions whether informal training is the optimal way for some groups to acquire new skills. Section 5 situates the issue of AET in the context of a strategy of human capital investment and provides a sense of what research priorities should be. Appendixes contain a statistical portrait of AET in Canada; summaries of major Canadian surveys of AET; and 48-item bibliography. (YLB)