Mentoring is proposed as an effective strategy for helping novice teachers develop professional knowledge. However, a recent analysis of mentor-novice conversations in the United States about teaching reveals that they may not be important to the development of teachers' reform-minded practice. While this might be the case involving student teachers or novice teachers, it might not necessarily reflect the nature of reflective conversations between more experienced mentees and their colleague-mentors. This case study explores the challenges and opportunities that peer mentoring (mentoring between two teachers with some degree of experience) create for learning to teach mathematics in the context of urban diverse school context. This case suggests that effective teaching, learning to teach, and mentoring share a similar feature. It also provides an example of a peer mentoring relationship that encouraged inquiry and reflective practice. (Contains 2 figures.)