Key Social Norms Take-aways This study provides strong evidence that transactional sex among adolescent girls and young women (AGYW) in Uganda is shaped by gender norms linking male financial provision to sexual decision-making power. Higher levels of male provision increase perceived social approval of men’s authority and sexual control within relationships, while simultaneously reducing peer approval of girls seeking multiple partners. These norms help reinforce unequal power dynamics that undermine girls’ sexual agency. The vignette method reveals how such norms operate implicitly, offering a valuable tool for identifying normative drivers of HIV and pregnancy risk.

Objectives To develop and test vignette-based methods for identifying gender norms linked to transactional sex that may heighten sexual and reproductive health risks among AGYW in Uganda.

Methods The study used a four-phase mixed-methods approach in Kampala and Masaka, Uganda: (1) analysis of secondary qualitative data; (2) 10 focus group discussions; (3) 32 cognitive interviews to refine vignettes; and (4) a pilot survey with 108 sexually active, unmarried AGYW aged 15–24. Three experimental vignettes were developed and tested using a 2×1 factorial design to manipulate the level of male financial provision. The experiment measured individual attitudes, descriptive norms, and injunctive norms related to male authority, sexual decision-making, and female partner concurrency.

Results Higher levels of male provision were associated with increased approval for male sexual decision-making power and greater perceived community support for male authority. Conversely, low provision from a male partner increased perceived approval from friends and peers for girls seeking a second, supportive partner. Girls who had practiced transactional sex were more likely to personally approve of partner concurrency. Across all domains, social approval was a function not only of behavior but also of provision, underscoring how provision is embedded in gendered expectations.

Conclusions Transactional sex in Uganda is governed by entrenched gender norms that link male provision to sexual entitlement and female subordination. These norms must be addressed through gender-transformative interventions that target community-level beliefs, promote sexual agency, and reduce dependence on male partners for financial security. The use of vignette experiments offers a promising strategy for measuring and ultimately shifting harmful social norms.