Mentoring in the United States emerged in the wake of industrialization as Americans were looking for a way to reduce childhood delinquency in more supportive and growth-focused ways than the correction systems in place. This chapter provides the historical context for mentoring in the United States from the early twentieth century through today. Over the years, mentoring has shifted from using a relationship to target delinquency in boys, to increasing access to resources for youth and families who may not otherwise have access, to providing intervention components that are intended to impact specific outcomes. The key historical research studies of mentoring are highlighted along with a description of new mentoring models.