A 4-Year RCT of Big Brothers Big Sisters: Crime Prevention and Positive Youth Development in Action

DuBois, D. L., Herrera, C., Rivera, J., Brechling, V., & Root, S. (2025). Randomized controlled trial of the effects of the Big Brothers Big Sisters Community-Based Mentoring Program on crime and delinquency: Four-year findings. Institute for Health Research and Policy, University of Illinois Chicago. https://www.bbbs.org/youth-relationships-study-2025 

Introduction

Despite widespread support for youth mentoring as a violence and crime prevention strategy, few evaluations have tracked its long-term effects. Addressing this gap, the Youth Relationships Study by DuBois and colleagues (2025) offers one of the most comprehensive tests to date of mentoring’s impact on delinquency-related outcomes. This large-scale randomized controlled trial (RCT) assessed the Big Brothers Big Sisters of America (BBBSA) Community-Based Mentoring (CBM) program over a four-year period, focusing on outcomes central to juvenile justice involvement and youth well-being.

Methods

In total, 1,353 youth were randomized to either receive immediate mentoring or delayed access, with data drawn from surveys and juvenile justice administrative records. Seventeen BBBSA agencies across the U.S. participated, representing geographic and organizational diversity. Eligible youth were at least 10 years old and had not previously been matched with a mentor. Participants were randomized in a 3:1 ratio to the treatment (n = 1,011) and control (n = 342) groups. Youth and caregivers completed baseline, 18-month, and four-year surveys. Arrest data were obtained for 73% of the sample. Intent-to-treat analyses assessed outcomes regardless of mentoring uptake, which reached 68% in the treatment group by Year 4. Primary outcomes included arrests, delinquent behavior, and substance use. Secondary outcomes spanned risk and protective factors, mental health, and academic and occupational outcomes.

Results

By Year 4, youth in the treatment group showed statistically significant reductions in violence-related (29.6% vs. 43.0%) and property-related delinquency (26.4% vs. 34.1%), and recurring substance use (18.2% vs. 31.4%). Although arrest rates were lower for the treatment group (9.4% vs. 13.4%), this difference was not statistically significant. Significant improvements were also seen in multiple domains: reduced aggressive behavior, fewer negative peer associations, and decreased depressive symptoms. Youth in the treatment group reported higher levels of self-control, hope for the future, academic performance, and occupational identity. Notably, suicidal ideation and high school dropout rates were significantly lower among mentored youth.

Discussion

This study upholds that structured, long-term mentoring through BBBSA’s CBM program can significantly reduce key precursors of criminal behavior, including violence, substance use, and depression. Although arrests did not differ significantly (likely due to systemic biases or incomplete records) other findings underscore mentoring’s protective effects across developmental domains. The CBM model’s strength appears rooted in the sustained, supportive relationships it fosters and its alignment with Rhodes’ (2005) developmental model of mentoring.

Implications for Mentoring Programs

These findings provide strong justification for continued investment in high-quality, community-based mentoring. Practitioners should note the importance of relationship duration and mentor support infrastructure. Given the reductions in risky behavior and increases in protective assets, mentoring programs should be integrated into broader youth development and crime prevention strategies. Programs serving high-risk youth populations (including those experiencing poverty, systemic racism, or parental incarceration) may especially benefit from scaling such models.

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