Book excerpt: This book, the third in a series on the life course, has significance in today's world of research, professional practice, and public policy because it symbolizes the gradual reemergence of power in the social sciences. Focusing on "self-directedness and efficacy" over the life course, this text addresses the following issues: * the causes of change * how changes affect the individual, the family system, social groups, and society at large * how various disciplines--anthropology, sociology, psychology, epidemiology--approach this field of study, with consideration given to common themes and differences Finally, an effort is made to develop a multidisciplinary perspective unique to the study of self-directedness and efficacy.