How has the role of adolescence, as a life stage, changed in post-industrial Western societies? Although itÆs clear that there has been a definite change across most cultures in this life stage, the array of ways it has changed is surprising. This issue of The Annals is devoted to understanding how and why different nations have organized the life course of youth - between the ages of eighteen and thirty-four - in different ways and examines the consequences of this reorganization.''The project sprang from a yearlong seminar at the Center for Advanced Study in the Behavioral Sciences (CASBS), sponsored by the Carnegie Foundation. IT began by mapping out what was known about the transition from adolescence to adulthood and then examining historical and cross-national date on departure from school, entrance into the labor force, setting up an independent household, marriage, and parenthood.''While a large amount of date existed, there was little analysis. So a series of papers (most of them included in this issue) were prepared. The objective was to look across the data sets to glean what could be learned from the causes and consequences of different 'regimes' of the transition to adulthood. Although there is still much work to be done in this field, this compilation of articles has made great strides toward understanding the how the life stage of adolescence is shaped across cultures and provides a solid foundation for further research.