The life course has emerged over the past 30 years as a major research paradigm. Distinctive themes include the relation between human lives and a changing society, the timing of lives, linked or interdependent lives, and human agency. Two lines of research converged in the formation of this paradigm during the 1960s; one was associated with an older ''social relationship'' tradition that featured intergenerational studies, and the other with more contemporary thinking about age. The emergence of a life course paradigm has been coupled with a notable decline in socialization as a research framework and with its incorporation by other theories. Also, the field has seen an expanding interest in how social change alters people's lives, an enduring perspective of sociological social psychology.