This paper draws from a case study of first year district implementation of the California Mentor Teacher Program in one of the largest districts in California. The paper focuses on the opportunities offered to teachers who work with mentors. Through the presentation of a selection of vignettes of teachers who worked with mentors, the paper suggests that the mentorship can provide the occasion for changing the norm of isolation to a norm of collegial assistance. Outcomes for teachers included companionship and assurance, access to models of teaching, adjustments in teaching practices, and, to a lesser extent, support for thinking about teaching. A secondary purpose of the paper was to describe some of the problems that several mentors encountered in asserting their role, such as the lack of organizational support, suspicion and jealousy from other teachers, and a dilemma about how to assert themselves. (Author)