Research in adult learning has probably progressed further and produced more definitive results than in any other area of adult education. E. L. Thorndike's study, "Adult Learning" and other studies have shown that--(1) adults can learn, and, given their own time, can learn as effectively in later maturity as in earlier adulthood, unless physically handicapped; (2) the processes of learning are now known to be more numerous and complicated than once imagined but adaptations in techniques and to the environment can improve the outcome of adult education; (3) while the amount of schooling makes a difference in later learning, the educationally disadvantaged can, and do, learn; (4) learning is most rapid when motivation is strong and goals are clear; and (5) in all adult educational programs the social situation in both community and group terms influences both participation and outcomes. Still unsolved problems to which research must be applied include the learning process, problem-solving behavior in nonschool and nontest situations, better measuring instruments and longitudinal studies, effects of experience, socioeconomic influences, motivations, values, and program design. (sg)