Interventions implemented outside of the juvenile justice system are widely utilized with youth offenders to decrease the likelihood of future offending and justice system involvement, both of which are well-documented as being costly to youth and society at large. Olsson et al. (2021) conducted a systematic review and meta-analysis of these types of interventions for youth aged 12-17 and failed to find any of the interventions examined to be more effective than control treatments in reducing future criminality. This commentary further examines the evidence for one of these interventions, mentoring, based on an expanded search of the literature that identified several additional studies of mentoring for recidivism prevention that meet the eligibility criteria utilized by Olsson et al. A meta-analysis of these studies and those identified by Olsson et al. finds mentoring to be more effective than control treatments (typically services as usual within the juvenile justice system): risk difference between groups of 0.09 (random effect model; 95% confidence interval .03-.15). This reanalysis thus indicates greater promise for mentoring as a tool in reducing juvenile crime and juvenile justice system involvement than was suggested by the results of Olsson et al. Importantly, it also underscores the potential for the results of meta-analyses to be sensitive to not only unidentified studies with null or negative results (the so-called "file-drawer problem") but also missed studies with positive findings. Recommendations for literature search procedures in systematic reviews and sensitivity analyses in meta-analyses are provided with this concern in mind.