Icehearts is a Finnish sport-based program targeted at children and adolescents with higher risk of social marginalization and mental health problems. The core aim of the program is to provide participating children with a long-term mentoring relationship that lasts throughout childhood and adolescence, for a total of 12 years. Ongoing participation in a team sport sets the context for the mentoring relationship. The work of Icehearts mentors can be divided into four areas: support in school and schoolwork, team sport as an after-school activity, child-specific individual support, and family support in collaboration with other services. This chapter describes the program, presents accumulated evidence on program outcomes, and discusses key challenges and potential pitfalls when implementing the program. Implications for future research, practice, and policy are discussed.