This study analyzed the effectiveness of a mentoring program in which 18 experienced teachers were released from teaching duties to act as full-time mentors for 10 new teachers each in an urban school district. Analysis of data gathered via surveys of and interviews with beginning teachers, principals, and mentors indicated that: (1) teaching in a large urban school district was problematic because of feelings of insignificance and isolation, late hires, changes of teaching assignments after hire, and placement in fields inconsistent with training or experience; (2) the most often stated need was for assistance in gaining knowledge of district and building policies and procedures, followed by the needs for resources, a clearer definition of what was expected of them, and more feedback on how they were doing; (3) almost all teachers who worked with mentors acknowledged gaining some benefit; (4) high school and specialty teachers were more inclined to be disappointed with a "generalist" mentor; (5) mentored teachers tended to seek out help from more people, more often, and for more needs than did nonmentored teachers; and (6) teachers identified as being "at risk" regarding retention included new teachers between the ages of 31 and 35, middle school teachers, whites, and those hired on short notice. (Contains 15 references.) (JDD)