This qualitative study examines mentors' interpretations of their practice as revealed through writing and discussing their cases in a university postgraduate course in Israel. The data were examined for emergent features of the practice of in-service mentoring in the Jewish and Arab sectors within the Israeli school system. Content analysis of the cases and of the discussions that followed their presentation in class revealed a unique "discourse of mentoring" or "language of practice" that reflected mentors' concerns over issues of "accountability" and "boundaries" of roles in their practice. From a programmatic perspective, the study reveals that a university teacher-education course based on case-method pedagogy constitutes a safe and challenging context for mentors to voice dilemmas inherent in their field experiences that are often silenced by the system. (Contains 2 tables and 3 notes.)