This article presents a study of mentor teachers who work with residents in an urban teacher residency program in New York City. Forty-six mentor teachers (i.e., cooperating teachers) were asked to describe moments of effective mentoring, as well as their own strengths, weaknesses, and goals as mentors. Implicit in mentor teachers' descriptions of effective mentoring were their perspectives on effective teaching. These perspectives offer much insight into the challenges of clinically rich teacher preparation for a particular urban context, raising several dilemmas that should be considered amid the calls for teacher preparation that is deeply rooted in field practice.