Erikson stated that healthy identity development during adolescence is a precursor of intimacy in romantic relationships during emerging adulthood. However, from a developmental contextual perspective, there are reasons to question this strict developmental ordering. Using interview and questionnaire data from a longitudinal study on 93 adolescents, the authors tested whether ego development in middle adolescence predicts intimacy in emerging adulthood. Second, the authors examined whether identity achievement at the transition to adulthood mediates this link. Results revealed direct links between early ego development (age 15) and intimacy in romantic relationships (age 25). No paths were found from earlier intimacy to later ego development. No gender differences occurred. Relational identity achievement, an integrative identity construct measured at age 24, fully mediated the association between earlier ego development and later intimacy. This study confirms Erikson’s old ideas on the developmental ordering of identity and intimacy for youngsters in the 21st century. Moreover, it highlights the integrative function of relational identity for later mature intimacy.