Two hundred and sixty‐five participants and their romantic partners were involved in a prospective, longitudinal, and multimethod study during the transition from adolescence to adulthood. Guided by the development of the early adult romantic relationships (DEARR) model (Bryant & Conger, 2002), the research (a) investigated mid‐adolescent family experiences and individual differences in personality as predictors of qualities in the early adult romantic union and (b) evaluated the degree to which marital beliefs mediated these associations. Structural equation modeling partially supported the mediating effects of marital beliefs. The findings were generally consistent with the DEARR model, suggesting that it is informative to study early adult romantic relationship functioning within a developmental‐contextual framework, while simultaneously considering the unique effects of personality and relationship cognitions.