This volume examines positive development across adulthood with particular emphasis on postformal thought. The editors acknowledge that researchers have compiled a substantial body of descriptive evidence about the styles of thinking used by adults under certain conditions. The questions that remain are whether these styles reflect qualitative changes; how these styles develop; whether there are necessary precursors; why there is content specificity; what the relationship is to physiological or neurological development; whether adults can deliberately control postformal thought; how postformal thought develops in different cultures; what key developmental experiences, if any, are needed for postformal thought to develop; and what postformal thought means in a practical sense. These questions are addressed by the research and theory discussed in this volume. The contributors reflect a diversity of backgrounds assumptions, disciplines, and methods. Postformal thought and its correlates are described from physiological, psychological, sociological, anthropological, and clinical perspectives.