This study uses nationally representative data from 2005 and 2023 to examine changes in young adults’ (ages 25-34 years old) experiences reaching five milestones of adulthood: living away from their parents, completing their education, labor force participation, marrying, and living with a child. Changes are considered for individual milestones, as well as for combinations of milestones. The types and combinations of milestones young adults experience have seen major shifts in the past several decades, with growth in the shares experiencing economic markers, and reductions in those who experience family formation events. Multi-level models and decomposition analyses reveal that changes in the association between certain characteristics – such as being male and living in metropolitan areas – and achieving markers of adulthood appear to contribute most to the overall declines in the share of young adults who experience all milestones. Findings from the current study shed light on changing pathways to adulthood.