Building upon previous literature reviews, this article highlights research and evaluation efforts regarding the effectiveness of mentoring programs for new teacher retention in the USA since 2005. Through the analysis of various mentoring program components, different research methods used, and major findings from these studies, we discuss the non-linearity and complexity of both the mentoring process itself and the study of mentoring on new teacher retention. Based on our review, we offer recommendations for researchers and decision-makers to enhance the quality of such studies and maximize the use of the findings in improving mentoring programs and enhancing teacher retention.Each year many teachers enter and leave the teaching profession in the United States. According to recent data from the National Center for Education Statistics (2010), of the 3,380,300 public school teachers who were teaching during the 2007-2008 school year, 8% left the profession (leavers) and 7.6% moved to a different school (movers). For new teachers, those who have one to three years of experiences, the turnover rate was even higher, with 9.1% leavers and 13.7% movers.Teacher turnover can be costly for school districts. In a pilot study conducted by the National Commission on Teaching and America's Future, for example, the total cost of teacher turnover in the Chicago Public Schools was estimated to be over $86 million per year, and the average cost per leaver was $15,325 (Barnes, Crowe, & Shaefer, 2007). High turnover costs undermine school districts' efforts to enhance the quality of teaching under the already tight budgets. Most importantly, higher school turnover rates have an adverse affect on student academic performance (Guin, 2004;Terry & Kritsonis, 2008).