Scholars--and adults in general--have pondered for centuries the mysterious processes that influence the ways in which children gradually become adults. The development of professional organizations and journals devoted to adolescence, as well as increasing appreciation in academia and the world of policy for the importance of this phase of life, have helped this field catch up with the pace of research on other stages of human development particularly infancy and early childhood. The development of a comprehensive review of research on adolescence depends in large part on the perceived need for such a synthesis and the extent to which different research fields as well as policy and practice would benefit from such an effort. To address these issues, the National Research Council and the Institute of Medicine, through the Board on Children, Youth, and Families, held a two-day workshop in September 2005. The workshop was designed as an opportunity for an interdisciplinary group to explore the different strands of research that contribute to understanding adolescence. In the brief time available, the group was not asked to address the entire range of issues related to adolescent health and development, but rather to provide an initial explanation of issues that a longer term study might address. A Study of Interactions summarizes the major themes discussed at the workshop. It begins with an overview of what adolescence is and current views of the processes that shape development in the second decade of life. It explores the transdisciplinary research issues already presented in this field, as well as issues raised in discussions of goals for the field's future. A closing section describes the presenters' thoughts on the feasibility of launching an in depth contextual study that could more firmly establish connections among the many fields of study concerned with adolescence.