This study considers the developmental origins of alcohol use in young adulthood. Despite substantial evidence linking committed romantic relationships to less problematic alcohol use in adulthood, the uniformity of these protective benefits across different romantic relationships is unclear. Further, the extent to which the establishment and maintenance of these romantic relationships is preceded by earlier adolescence alcohol use remains unknown. To address these gaps in the literature, the current study utilized multitiple-dimensional, multiple-informant data spanning 20 years on 585 individuals in the Child Development Project. Findings from both variable- and person-centered analyses support a progression of associations predicting adolescent alcohol use (ages 15–16), drinking, and romantic relationships in early adulthood (ages 18–25), and then problematic young adult alcohol use (age 27). Although adolescent alcohol use predicted greater romantic involvement and turnover in early adulthood, romantic involvement, but not turnover, appeared to reduce the likelihood of later problematic drinking. These findings remained robust even after accounting for a wide array of selection and socialization factors. Moreover, characteristics of the individuals (e.g., gender) and of their romantic relationships (e.g., partner substance use problems and romantic relationship satisfaction) did not moderate these findings. Findings underscore the importance of using a developmental–relational perspective to consider the antecedents and consequences of alcohol use early in the life span.