In this study, age-related differences in adults' moral identity were investigated. Moral identity was conceptualized a context-dependent self-structure that becomes differentiated and (re)integrated in the course of development and that involves a broad range of value-orientations. Based on a cross-sectional sample of 252 participants aged 14 to 65 years (148 women, M = 33.5 years, SD = 16.9) and a modification of the Good Self-Assessment, it was demonstrated that mean-level of moral identity (averaged across the contexts of family, school/work, and community) significantly increased in the adult years, whereas cross-context differentiation showed a nonlinear trend peaking at the age of 25 years. Value-orientations that define individuals' moral identity shifted so that self-direction and rule-conformity became more important with age. Age-related differences in moral identity were associated with, but not fully attributable to changes in personality traits. Overall, findings suggest that moral identity development is a lifelong process that starts in adolescence but expands well into middle age.