This study examined whether the transition into adolescence, proxied by pubertal timing, shaped the transition into adulthood, proxied by union formation behaviors, among contemporary American women. In a sample drawn from Add Health (n = 7,523), early maturing girls reported an accelerated transition to marriage and cohabitation in young adulthood, net of family structure history, academic achievement in high school, and parental education. The link between pubertal timing and cohabitation was strongest among socioeconomically advantaged women; no socioeconomic differences were identified for marriage. The tendency for early maturers to have more pronounced romantic orientations during adolescence partially explained their transitions to marriage. In all, the persistence of the pubertal timing effect into young adulthood suggests that early maturers accelerated entrance into the romantic market in adolescence has a cascading, long-term impact on the shape of their lives in young adulthood. (Contains 5 tables, 1 figure, and 1 note.)