The goal of this trial is to test the effectiveness of a brief, behavioral peer group intervention called "PEGISUS" (Peer Education for Gender Inclusion and Substance Use in Southern Africa), on substance use, which will be embedded within existing vocational training programs in Zambia, Zimbabwe, and South Africa. Established peer groups who receive the PEGISUS intervention will complete nine sessions of an adapted intervention for substance use and gender equitable beliefs, embedded into vocational training programs. This will be compared to a standard of care control condition, which involves the vocational training program that is offered through the partner organization and a healthcare referral for substance use. The vocational training program partners are Sozo Foundation (South Africa), BuildIt International (Zambia), and Masvingo Polytechnic (Zimbabwe). Participants in both conditions will complete assessments at baseline, 12-weeks follow-up, and 24-weeks follow-up, consisting of self-reported questionnaires.

Adolescents and young adults (AYA) make up a large proportion of the population in sub-Saharan Africa (SSA), including in South Africa, Zambia, and Zimbabwe, but also face increasingly high levels of disability and mortality. This is influenced by high levels of substance use and occurs in a predominantly gender normative environment that places young men, women, and non-cisgender young people at risk. One of the primary risk factors for AYA substance use is having peers who also engage in substance use, however, treatments do not target peers. Adoption of traditional gender norms that favor men are also associated with worse health outcomes for both genders. For AYA boys/men, this includes substance use, sexual risk-taking behaviours, and engaging in intimate partner violence; for AYA girls/women, there is increased risk of acquiring sexually transmitted infections and HIV as well as poor educational attainment, such as school dropout. It is necessary to target such gender norms to improve health outcomes of both genders. Addressing these traditional gender beliefs during the AYA period may be more impactful than during adulthood. AYA education and/or vocational training (VT) programs increase chances for a successful future in a setting where employment of youth is generally low. Overall, key behaviors during the AYA period in SSA support well-being across the lifespan, including educational/ vocational attainment, developing healthy coping beyond substance use, and adoption of equitable gender norms. This study seeks to test a brief, behavioral intervention focused on substance use reduction and development of equitable gender norms, which will be delivered to peer groups enrolled in existing VT programs in South Africa, Zambia, and Zimbabwe.

Inclusion Criteria:

• Adolescents and young adults 16 - 24 years old
• At least weekly self-reported alcohol/drug use in a peer group in the past month or at least monthly heavy episodic drinking with peers over the past three months
• Comfortable communicating in the predominant local language or English
• Lives in the target community and plans to remain in the area for the next 12 months
• Eligible to participate in the vocational training (VT) program (according to the VT program's own entry guidelines) and willing to participate in the entirety of the program
• Interested to participate in a substance reduction and gender equity beliefs program and able to identify 2 to 5 peers to join
• Willing to have PEGISUS workshop sessions audio/video-recorded (if assigned to that group)

Exclusion Criteria:

• Untreated major mental illness that interferes with study participation, such as active suicidality, or unmanaged bipolar disorder or psychotic disorder
• Currently receiving psychological treatment for substance use
• Participation in another VT/skills development program or another trial that is judged by the site investigator as non-compatible with this study
• Unable to provide informed consent or informed assent

The relevant anonymized data and statistical code will be deposited alongside the published peer-reviewed papers, in alignment with data sharing and verification procedures. Other investigators wishing to access the data for additional analyses can contact the study PI so that the appropriate documents (e.g., data sharing, ethics approvals) can be arranged.

A de-identified dataset will be deposited in an open-access data repository at the end of the project and once the objectives specified in the protocol have been addressed.

The data can be accessed by the public, through creation of an account with Open Science Foundation, an open-access data repository.