Youth mentoring is the process of matching mentors with young people who need or want a caring, responsible adult in their lives. Adult mentors are usually unrelated to the child or teen and work as volunteers through a community-, school-, or church-based social service program.

Although informal mentoring relationships exist, formal, high-quality mentoring matches made through local or state mentoring organizations are often the most effective.

According to the encyclopedia of informal education:

"The classic definition of mentoring is of an older experienced guide who is acceptable to the young person and who can help ease the transition to adulthood by a mix of support and challenge. In this sense it is a developmental relationship in which the young person is inducted into the world of adulthood."

In 2002, the Institute of Medicine of the National Academy of Sciences published a major report examining after-school and other community programs designed to foster positive youth development. The report concluded that very few after-school programs ?have received the kind of comprehensive experimental evaluation necessary to make a firm recommendation about replicating the program in its entirety across the country.? However, the report singled out mentoring programs modeled after the Big Brothers Big Sisters mentoring program as a rare exception, and recommended its widespread replication.