The self-concept is a hierarchical, multi-faceted cognitive structure that is composed of four self-domains: individual, relational, group, and ecological. Four routes to self-concept change were proposed (individual, relationship, group, and ecological), and the influences of these routes on each of the four self-domains and psychological well-being were investigated. One hundred thirty-six undergraduates participated in this three-wave study (117 returned at Time 2 eight weeks after the first session, and 61 returned again at Time 3 during the first two months of the second semester). At Time 1, they generated an open-ended list of self-descriptors, and a questionnaire that consisted of pre-selected self-domain, expectations of change, attempts at change, and well-being measures. They then rated the amount of contact they had with seven people, seven groups, and their home environment. For the second and third sessions, participants received their original self-descriptors list, and were asked to cross-off any of the items on the list they believed were irrelevant in their current environment (maintenance failure), and to add any statements to the list that were new self-aspects (self-expansion). The remainder of the session proceeded in the same manner as at Time 1, except participants re-rated the frequency and quality of contact with the people from the relationships/groups lists from Time 1. Results using bivariate correlation, regression, and structural equation modeling analyses showed that the process through which most change occurs is through contact with new relationships (the relationship route), but the volitional attempts at change (the individual route) also predicted self-concept change. Contact with new social groups (the group route) was associated with higher levels of psychological well-being, and contact with the new environment as a whole (the ecological route) was associated with self-expansion. The findings also provided some evidence that individual differences in expectations moderated some of the effects of the routes on the self-domains. These results suggest that self-concept change during the transition to college can mostly be understood through the change in one's social environment. Implications for other relocation instances and psychotherapy are discussed.