The transition from adolescence to adulthood is marked by changing roles and responsibilities, self-discovery, and boundary-testing. This journey is reflected in an evolving relationship with alcohol. It is generally accepted that high-risk drinking during this period is symbolic of experimentation with independence, eventually transitioning into a process of “maturing out” that results in drinking patterns more compatible with adult roles and responsibilities. Yet more recent research indicates that the drinking trajectory during this period is neither predictable nor necessarily sequential, but subject to considerable variation. Numerous individual and group factors, as well as broader cultural and societal shifts, play determining roles in its progression. Over recent decades, the timing of life stages, perceptions of appropriate roles and behaviors, and macro-level global trends have shifted and with them the trajectory of drinking from adolescence into adulthood. Drawing largely from the epidemiological literature, this chapter explores the role played by the many factors involved. They include gender, family and peer relationships, employment, and parenthood, as well as changing definitions and perceptions of adolescence and adulthood and the changing social saliency of drinking in the lives of some young people.