Turnover among volunteers and paid staff in community-based organizations serving youth and families is high, with negative consequences both in the organizational resources expended on training new hires and on youth and family who may not be as well served by novice helpers or helpers experiencing burnout. Attrition is particularly concerning in youth mentoring given that the intervention hinges on the development of meaningful relationships. In this study, we interviewed paid staff of a professional youth mentoring organization, all of whom were employed by the organization for 10 years or more—some continuously as mentors, and others first as mentors and then in leadership positions. We sought to learn from individuals who have made the decision and had the ability to remain in the organization for many years to identify personal, organizational, community-level, and macro-contextual factors that may influence attrition/retention, including factors that could be modified by organizations. Participants described the professional mentoring program model and professional mentor role as impactful for youth and families and personally rewarding, and thus as a contributor to their retention; however, they also described the emotional toll the work could take, which they observed contributing to others’ departures. Their experiences with training, supervision, and other organizational factors informed their sense of whether they felt supported and valued, which they identified as a driver of attrition/retention. Professional mentoring and other youth-serving organizations may enhance retention by including frontline workers in decision making, responding to workers’ needs, and seeking balance between sufficient scaffolding and the promotion of autonomy.