This discussion reports data from a 4-year longitudinal evaluation of a project from the United Kingdom. The project focused on outdoor activities as a vehicle for enhancing the personal and social development of disaffected youth with the researchers specifically examining the role played by volunteer learning mentors. Following a summary of relevant literature and an overview of the project design and evaluation strategy, data are reported on the impact and effectiveness of these mentors. The findings suggest the potential for mentors to function as informal educators in such youth programs. However, a lack of preparation and the considerable challenges faced in establishing and maintaining mentoring relationships with young people in schools can restrict their impact. It is argued that similar future initiatives would benefit from greater pre-planning and an improved understanding of how mentors and other youth professionals can work with each other. (Contains 5 notes and 2 tables.)