In 2012, the Office of Juvenile Justice and Delinquency Prevention (OJJDP) launched a demonstration field experiment, the Mentoring Enhancement Demonstration Program (MEDP) and Evaluation to examine: (1) the use of an "advocacy" role for mentors; and (2) the use of a teaching/information provision role for mentors. The overall goal of MEDP was to develop program models that specified what advocacy and teaching look like in practice and to understand whether encouraging the general practice of advocacy and teaching could improve youth outcomes. The American Institutes for Research (AIR) conducted a rigorous process and outcome evaluation of programs funded by OJJDP in 2012. The evaluation was designed to rigorously assess the effectiveness of programs that agreed to develop and implement enhanced practices incorporating advocacy or teaching roles for mentors, including providing focused prematch and ongoing training to mentors, and providing ongoing support to help mentors carry out the targeted roles.MEDP grantees comprised collaboratives that would offer coordinated implementation of the same set of program enhancements in three or four separate established and qualified mentoring programs located within the same regional area. The MEDP collaboratives varied widely in their geographical locations, their size and experience in mentoring, and the structure of their mentoring programs. The types and structures of mentoring programs also varied across, and sometimes within, collaboratives. All the collaboratives proposed enhancements in the way they would train mentors for their roles, and in the way they would provide ongoing support to the mentors and in some cases the youth that they were matched with. This data collection consists of multiple types of respondents (youth, parents, mentors, and staff) across multiple data collection periods.