Strengths-based, goal-focused approaches to working with at-risk youth have been successfully used by mentoring programs, therapeutic interventions, prevention programs, and self-help groups. However, few such approaches have been used to inform juvenile diversion programs. This is partially explained by limited empirical research on mechanisms of change used by goal-focused interventions in populations of young offenders. The authors use goal-setting theory to explore the effects of goal commitment and solution building on program completion, in a sample of violent first-time offenders (N = 159). Mediation effects of solution building in the relationship between goal commitment and program completion were tested using both Baron and Kenny’s and Preacher and Hayes’s approaches. Results showed that high goal commitment and solution building were significant predictors of program completion. In addition, solution building fully mediated the impact of goal commitment on program completion. Implications for research and practice are discussed.