This paper summarizes what is known and what is not known about mentoring programs focused on youth and related to college-going. Several aspects of mentoring are reviewed so that the concept and some program variations--such as peer and adult mentors, informal and formal mentoring, compensated and uncompensated mentoring, one-to-one and group mentoring, and young adult versus adolescent mentees--are understood. Four commonly held and untested assumptions about mentoring are examined: (1) that mentoring is always a good idea; (2) that erratic mentoring is better than no mentoring; (3) that mentoring increases academic achievement and college-going; and (4) that mentoring is inexpensive. Research suggests that many mentoring programs aim to accomplish goals that do not appear to be achievable through mentoring, e.g., academic improvement. However, mentoring programs, when properly designed, can achieve several important outcomes (although they are often different than those commonly touted in the literature and have a much less significant impact than usually stated). Given that research indicates that mentoring as an intervention is weak compared to other social science interventions, it is important to consider the costs as well. Practitioners need to be sure that they are trying to achieve viable goals. While it may not be statistically significant in advancing college-going as identified through grades or academic achievement, mentoring certainly fosters aspirations for college, builds self-esteem, motivates students to focus on academic achievement, provides valuable information about academic standards and norms for college-going, and decreases problem behaviors that can impede academic success and continuation. Each of these areas may have a mediating effect on college-going. Mentoring can be harnessed for its strengths, rather than focusing on goals it is not well equipped to meet. [This report was published by the Center for Higher Education Policy Analysis, Rossier School of Education, University of Southern California.]