In Circles of Support and Accountability (CoSA), volunteers support a medium- to high-risk sex offender in his process toward desistance by developing a long-term empathic relationship. More knowledge is needed about the impact of this work on volunteers themselves. In a sample of 40 Dutch CoSA volunteers—at the time constituting 37% of the national population of 108 then active CoSA volunteers—we measured outcome in terms of volunteer satisfaction, determination to continue, compassion satisfaction, burnout and secondary stress, vicarious growth, civic capacities, and professional skills. We explored theoretically derived predictors of positive and negative outcome, and conceptualized them within the Job Demands-Resources model (JD-R). Volunteers reported mainly positive effects, especially high levels of volunteer satisfaction, compassion satisfaction, and determination to continue. Results indicated that job demands and most of the internal job resources were of minor importance. External job resources, especially social support and connectedness, were associated with positive outcome. Connectedness mediated the effect of social support on compassion satisfaction.