Research and theoretical literature about adult development and adult learning are synthesized within a conceptual framework that has three basic domains: life phase, developmental stage, and learning style. The life phase includes theories that identify age-linked periods of stability and transition throughout adulthood. The development stage refers to structural dimensions of intellect, character, and personality organization. Learning style includes research on individuals' characteristic predilections and preferences for certain functional modes of learning over others, both cognitively and behaviorally. For each area, the parameters of the construct are defined, key concepts are identified, major representative theories are reviewed, and the implications of the viewpoint for adult education are discussed. A large proportion of the text deals with the domain of the developmental stage. Implications for educational practice are analyzed on three levels: individual uses, institutional uses, and societal uses. A major premise of the paper is the idea that adults develop, and that educational programs and opportunities, and some of the resources of society, ought to be organized in ways that are responsive to adults' developmental needs. (SW)