This report looks at changes in young adulthood over the last 40 years. It focuses on how the experiences of today’s young adults differ, in timing and degree, from what young adults experienced in the 1970s—how much longer they wait to start a family, how many have gone to college, and who are able to live independently of their parents. This report looks at a snapshot of the young adult population, defined here as 18 to 34 years old, and focuses on two periods: 1975 and today (using data covering 2012 to 2016 to reflect the contemporary period). Many of the milestones of young adulthood are reflected in the living arrangements of young people: when they move out of their parents’ home and when they form families. Because these milestones are tied to young adults’ economic security, the report also focuses on how education and work experience vary across young adult living arrangements.