Some of the best current work on the development of motivation is presented in this fortieth volume of the Nebraska Symposium on Motivation. The diverse approaches for conceptualizing and studying motivational development psychology that extends the traditional area of achievement motivation. Some major themes emerge: the conceptualization of the self, the internal and external factors that affect development of motivations, and the choices that result from one's motivations. Richard Ryan's opening chapter places the entire work in context by describing historical and theoretical perspectives on developmental and psychosocial models used to understand motivation. Mihaly Csikszentmihaly and Kevin Rathunde also focus on intrinsic motivation, but with a greater focus on "flow," the experience of full involvement with an activity. Susan Harter discusses the roles of the I-self and the me-self research models. Jacquelynne S. Eccles stresses the link between the social contexts of family and school and the motivational constructs related to achievement and choice of activity. Laura L. Carstensen maintains Eccles's focus on the importance of choice of activity, but concentrates on the later stages in life when social contact declines as a result of changing social and emotional motivations. The volume concludes with a summary analyzing the contributors' descriptions of the diverse but complementary aspects of developmental processes and theory.