If the teaching profession is to attract the most promising teacher candidates and retain those who are exemplary in practice, it is imperative that teachers' personal needs be attended to throughout their professional careers. In order to adequately address these needs, those designing preservice and inservice professional development must consider two important concepts associated with training: the developmental stages of adulthood and the stages of teachers' careers. Understanding the fascinating and complex intersection of these twin concepts may help those accountable for structuring educational policy and practice to implement programs that promote personal growth and fulfillment for teachers. This paper provides an overview of the literature summarizing adult development and the implications for learning at different stages of the adult life cycle. It then looks at patterns of teacher careers that describe the stages of their professional growth. Finally, it discusses how these two concepts interrelate and the implications for teacher training and educational policy. (Author)