While teachers can tell us wonderful stories of success, anecdotes and other informal assessments are not enough in an age of accountability. In Prince George’s County Public Schools (Maryland), our evaluation processes helped us blend soft data with hard data — and helped us learn key lessons in the process, both about building a mentoring program and refining it. OUR BEGINNING Prince George’s County Public Schools, the nation’s 17th-largest school system, began a Mentor Teacher Program in 1997 after the state required the district to provide new teachers in low-performing schools and schools with high teacher turnover with master teachers to guide their professional growth. The district regularly hires more than 1,200 newcomers a year in a system of more than 8,500 teachers, and the