Conceptions of the transition to adulthood in the contemporary American majority culture are examined, and compared to conceptions cross-culturally and historically. Perspectives from other places and times are presented first, indicating that there is a widespread view that the transition to adulthood involves the gradual development of character qualities such as impulse control and diligence but culminates in marriage as the ultimate marker of the transition to adulthood. Findings from several recent American studies are then presented, indicating that for contemporary young Americans the preeminent criteria for the transition to adulthood are the individualistic character qualities of accepting responsibility for one’s self and making independent decisions, along with becoming financially independent; marriage, in contrast, ranks very low. New data are presented to illustrate young Americans’ conceptions of the transition to adulthood. Reasons are discussed for the prominence of individualistic criteria in American society and the prominence of marriage in other places and times. The concept of emerging adulthood is presented as a new way of conceptualizing the period between adolescence and young adulthood.