The purpose of this study is to evaluate the effectiveness of the Big Brothers Big Sisters of America (BBBSA) community-based mentoring (CBM) program for prevention of crime and delinquency/conduct problems, including risk and protective factors for these outcomes. Approximately 2,500 youth ages 10-16 will be randomly assigned to either the CBM program or an untreated control group. Study outcomes will be assessed over a 4-year period via both youth- and parent-report surveys and official records of police/court contact (e.g., arrests).

The purpose of this study is to evaluate the effectiveness of the Big Brothers Big Sisters of America (BBBSA) community-based mentoring (CBM) program for prevention of crime and delinquency/conduct problems, including risk and protective factors for these outcomes. Participants will be recruited from 16 BBBSA affiliates, which are located in different regions of the U.S. and were invited to serve as sites for the study using a random selection process. The study sample will consist of approximately 2,500 youth ages 10-16 whose parents seek services from one of the participating BBBSA affiliates during the study enrollment period and for whom consent/assent to participate in the research is obtained. Enrolled youth will be randomly assigned to participate in the CBM program (treatment group) or to a control group (no BBBSA programming during the youth's 4-year period of study participation). Youth will be assigned in a 3:1 ratio to the treatment and control groups. Youth and parents will complete survey measures both at study enrollment, prior to notification of assignment to control or treatment group, and 18 months later. Official records of police/court contact (e.g., arrests), with separate parent/guardian consent as provided at study enrollment, will be obtained both for the period preceding each youth's enrollment in the study and for a 4-year period following enrollment.

The study has 4 specific aims:

1. To determine the effects of participation in the Big Brothers Big Sisters CBM program on youth offending as measured by police/court records, i.e., person offense, property offense, drug law violation, public order offense, or status offense.
2. To determine the effects of participation in the BBBS CBM program on the likelihood of youths' involvement in delinquent behavior/conduct problems as assessed by youth and parent reports.
3. To determine the effects of BBBS CBM program participation on the likelihood of youths' involvement in substance use as assessed by self-reports of alcohol use to point of drunkenness, tobacco, or illicit drug use.
4. To determine the effects of BBBS CBM program participation on both risk and protective factors for delinquent/criminal behavior, such as aggression, depressive symptoms, association with deviant peers, self-control, and school connectedness, as assessed by youth and/or parent reports, and to explore the role of these effects in mediating effects of program participation on offending, delinquent behavior, and substance use.

Inclusion criteria:

• youth is 10 years of age or older
• youth is likely to be eligible for the Big Brothers Big Sisters Community-Based Mentoring program as determined by initial assessment of program staff

Exclusion criteria:

• youth has a severe learning, cognitive or other intellectual disability as reported by the parent
• parent does not both speak and read either English or Spanish
• youth does not have a sibling who is already a study participant
• youth has been matched with a Big Brother/Sister through one of the affiliate's programs in the past
• youth has a sibling currently receiving services from the affiliate for whom services were initiated (i.e., inquiry was made) prior to start of the study
• youth belongs to a group that the affiliate is excluding from study participation based on previous agreement with the research team
• youth is designated as an exception case by affiliate staff (each affiliate will have the opportunity to exclude up to 4% of study-eligible youth from the research prior to consent and random assignment for any reason deemed appropriate (e.g., perceived high need of the youth))

At the study's conclusion, all individual participant data will be de-identified and made publicly available on the Open Science Framework website along with survey instruments and any code used to clean and analyze the data.

Data will become available August 2024 and will be permanently available thereafter

Requests to access the IPD will be made in writing to the Principal Investigator and approved so long as there is a valid scientific rationale and appropriate IRB approval. The mechanism for sharing the data, all of which will be de-identified, will be secure and encrypted FTP and subject to approval of the PI's institutional IRB. Supporting information (see above list) will be available on the Open Science Framework at the web address below.

The research team will collect the 18-month follow-up surveys from participating youth and parents; masking of study condition will not be feasible for data collection staff, but primary study analyses will be conducted by the investigators with study condition masked. Juvenile justice authorities providing arrest record information will be masked to study arm of participants as will all those on the research team who are involved in coding this information.