Three traditions of social theory are examined in this article, with a special emphasis being given to the ways that the concept of "generation" has been conceived and developed over time. These include Psychodynamic, Sociological, and Gerontological approaches with attention drawn to the similarities and differences among them. It is concluded that while conceptual development has been uneven, taken together, they provide a rich basis for a critical examination of contemporary social problems with implications for policy toward intergenerational relationships.This article examines the way the concept of generation has been used in various theories and approaches to the adult lifecourse. Generation goes to the heart of a number of debates about the nature of contemporary society. It has biological roots through the family, where generations generally refer to successive parentchild bonds. There are psychological dimensions in the sense of belonging and identity that can arise, depending upon the stance that an individual takes toward the generation in question. Generation is also used to locate particular birth cohorts in specific historical and cultural circumstances, such as the "baby boomers." It is a truly crossroads phenomenon that links a number of different fields and levels of analysis.The adult lifecourse, and its influence on intergenerational relations, is in a period of considerable flux. Scientific advances promise to extend the lifecourse, there are social and economic concerns about the sustainability of society's payas-you-go approach to pensions, and lifestyle changes appear to be redefining traditional roles and aspirations associated with later life. Each of these factors will influence the way that succeeding generations define each other and the degree of solidarity and rivalry that might result.