The evaluation was designed to assess the effectiveness of programs that agreed to develop and implement enhanced mentoring practices that incorporated advocacy or teaching roles for mentors, including providing focused pre-match and ongoing training and support for mentors. Participants in OJJDP's Mentoring Enhancement Demonstration Program (MEDP) were committed to developing mentoring program models that feature advocacy and teaching as means of improving youth outcomes. MEDP grantees were expected to offer coordinated implementation of the same set of program improvements in three or four separate established and qualified mentoring programs located in the same regional area; however, the types and structures of mentoring programs also varied across and sometimes within collaboratives. The evaluation of MEDP was designed to provide rigorous evidence on whether the enhancements improved youth outcomes and reduced risk for delinquency, and it describes the practice models and program characteristics associated with these improvements. The evaluation found that mentors who received a higher dosage of the programmatic enhancements had stronger relationships with their mentees and produced more positive outcomes in their mentees. The better outcomes across the various proximal, intermediate, and longer terms were more likely linked to the teaching functions than the advocacy functions. Thus, staff support for the teaching and advocacy functions had the greatest influence on shaping mentor behavior.