Mentoring programmes show significant promise for enhancing the well‐being of youth with complex needs. Research indicates that high quality mentoring, although difficult to achieve, positively impacts youth development across behavioural, social, emotional and academic domains. The difficulty of sustaining long‐term matches between mentors and youth, however, remains an important concern for the field of mentoring, as foreshortened matches can be harmful to youth. The 4Results mentoring programme has been identified as a Promising Practice through the Washington State Inventory of child‐serving behavioural and mental health programmes and has developed a unique infrastructure to support critical programme values such as match longevity. In 7 years, the programme has successfully retained 98% of mentors for at least 1 year with an average match length of 3.7 years. The following article describes the programme's guiding philosophy and approach to recruiting and training mentors in the context of existing best practices research.