The present study examined how the self-concept changed and what influenced the change in social interaction. Two hundred and fifty-nine (259) undergraduates, 90 men and 169 women, participated in the study. They were asked to recall an occasion when a change occurred to their self-concept because of an interactional influence by another person, and complete a questionnaire concerning the occasion. Main results were as follows: (1) Self-concept changes due to such influence were classified into five categories: enhancement, organization, confusion, discovery, and understanding identity. (2) Interdependence and role behavior expectations between the two at the occasion were examined and several of their aspects had influences on the self-concept change. These results were discussed in the context of developmental processes of close relationships.

Key words: self-concept, interpersonal relationship, developmental process of close relationship, interdependence, role behavior