Today, young people are transitioning to adulthood later in life than they were in the 1960s and 70s. Why has this change occurred and what does it mean for young adults, their families, and the larger society? This article discusses the transition to adulthood from an historical perspective. It then explores the challenges of this later transition for vulnerable youth and discusses a few of the many policy changes which can support them. (Contains 1 figure and 1 table.)