Social development over one's lifetime is a complex area that has received consider able attention in the psychological, social-psychological, and sociological literature over the years. Surprisingl~ however, since 1969, when Rand McNally published Goslin's Handbook of Socialization, no comprehensive statement of the field has appeared in book form. Given the impressive data in this area that have been adduced over the last two decades, we trust that our handbook will serve to fill that gap. In this volume we have followed a lifespan perspective, starting with the social interactions that transpire in the earliest development stages and progressing through childhood, adolescence, adulthood, and, finall~ one's senior years. In so doing we cover a variety of issues in depth. The book contains 21 chapters and is divided into five parts: I, Theoretical Perspectives; II, Infants and Toddlers; ill, Children and Adolescents; Iv, Adults; and V, The Elderly. Each of the parts begins with introductory material that reviews the overall issues to be considered. Many individuals have contributed to the final production of this handbook. Foremost are our eminent contributors, who graciously agreed to share with us their expertise. We also thank our administrative and technical staff for their assistance in carrying out the day-to-day tasks necessary to complete such a project. Finall~ we thank Eliot Werner, Executive Editor at Plenum, for his willingness to publish and for his tolerance for the delays inevitable in the development of a large handbook.