Cooperating teachers' beliefs of effective supervision of student teachers may play an important role in mentoring practices. By systematically analysing metaphors unconsciously expressed in the discourse of cooperating teachers concerning supervision of student teachers, these beliefs could be made explicit. This study explored: (1) what metaphors concerning supervision of student teachers are embedded in the cooperating teachers' everyday language; and (2) what central concept of effective supervision of student teachers is shared by the cooperating teachers' metaphors. Analyses of the interviews with the 13 cooperating US teachers showed that their metaphors centred on the issues of interpersonal relationships, power sharing, and tension and conflict. The metaphors converged into a central concept of a non-authoritative approach to supervision of student teachers that embraces relationship issues raised by the participants and provides successful learning experiences for student teachers. A recommendation for future research is suggested. (Contains 1 table.)