ABSTRACT: BACKGROUND:The HIV epidemic in Eastern and Southern Africa is characterized by a high incidence and prevalence of HIV infection among adolescent girls and young women (AGYW) aged 15-24 years. For instance, in some countries, HIV prevalence in AGYW aged 20-24 years exceeds that in AGYW aged 15-19 years by 2:1. Sauti (meaning voices), a project supported by the United States Agency for International Development, is providing HIV combination prevention interventions to AGYW in the Shinyanga region, Tanzania. OBJECTIVE:The aim of this study is to determine the impact of cash transfer on risky sexual behavior among AGYW receiving cash transfer and HIV combination prevention interventions. This paper describes the research methods and general protocol of the study. Risky sexual behavior will be assessed by herpes simplex virus type 2 (HSV-2) incidence, compensated sex (defined as sexual encounters motivated by exchange for money, material support, or other benefits), and intergenerational sex (defined as a sexual partnership between AGYW and a man 10 or more years older). Through a qualitative study, the study seeks to understand how the intervention affects the structural and behavioral drivers of the HIV epidemic. METHODS:The trial employs audio computer-assisted self-interviewing, participatory group discussions (PGDs), and case studies to collect data. A total of 30 matched villages (15 intervention and 15 control clusters) were randomized to either receive cash transfer delivered over 18 months in addition to other HIV interventions (intervention arm) or to receive other HIV interventions without cash transfer (control arm). Study participants are interviewed at baseline and 6, 12, and 18 months to collect data on demographics, factors related to HIV vulnerabilities, family planning, sexual risk behavior, gender-based violence, and HSV-2 and HIV infections. A total of 6 PGDs (3 intervention, 3 control) were conducted at baseline to describe perceptions and preferences of different intervention packages, whereas 20 case studies are used to monitor and unearth the dynamics involved in delivery and uptake of cash transfer. RESULTS:The study was funded in June 2017; enrollment took place in December 2017. A total of two rounds of the follow-up survey are complete, and one round has yet to be conducted. The results are expected in December 2019 and will be disseminated through conferences and peer-reviewed publications. CONCLUSIONS:This study will document the synergetic impact of cash transfer in the presence of HIV combination prevention interventions on risky sexual behavior among out-of-school AGYW. The results will strengthen the evidence of cash transfer in the reduction of risky sexual behavior and provide feasible HIV prevention strategies for AGYW. TRIAL REGISTRATION:Clinicaltrials.gov NCT03597243; https://clinicaltrials.gov/ct2/show/NCT03597243. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID):DERR1-10.2196/14696.