Just who is the adult learner and how is that learner best understood? Are adult learners defined by their intelligence (IQ), practical skills, knowledge, expertise or wisdom? What impact does stage of life and past experience have on the learner and learning, and just what status should be given to the prior learning adults bring? What distinguishes the adult learner from the child and at what point (if any) can we confidently separate our conception of the two? How do adults approach learning and in what ways might the findings of disciplines such as lifespan-development psychology and sociology inform the work of adult educators and trainers? These and other similar questions provide an introduction to the project of understanding the cognitive and developmental attributes of the adult learner, an essential study for those who wish to facilitate learning in the post-school years. As lifelong learning becomes the norm, the issue takes on an increasing urgency.