Social norms are the shared expectations about behaviors that are held within collective groups. These differ from attitudes and beliefs, which are individually held. In South Sudan, social norms can affect the use of voluntary family planning and reproductive health (FP/RH); some of these norms even present risks for women seeking FP/RH care and their FP/RH providers. This cross-sectional, descriptive study conducted in 5 counties in South Sudan used vignettes as a qualitative method to explore social norms related to FP/RH and decisions related to contraceptive use and gender-based violence. Participants were asked to respond to vignettes about a fictional couple during various life stages of care-seeking. Vignettes allow respondents to share their opinions and feelings without directly speaking about their own experiences. Respondents included community members, FP/RH providers, and key influencers (e.g., religious leaders, traditional leaders, elders). The study identified restrictive social norms related to FP/RH, including entrenched, dominant gender roles (i.e., requiring male consent to use contraceptives) and risk for the woman and her provider if she accesses FP/RH services. Of note, supportive social norms are gaining acceptance regarding women's voice and agency; it was found that some women can negotiate their reproductive choice with their partners and participate in planning their families, which has not always been a widely accepted norm. The use of vignettes can lead to a better understanding of the challenges and provide insights on effective implementation approaches. It is essential for programs working to promote the use of FP/RH services in South Sudan to consider the challenges presented by social norms. Findings from this study were shared with stakeholders and communities to codesign interventions aimed at increasing the use of FP/RH services. Additionally, the dialogue stimulated by this study should lead to an organic transformation toward supportive social norms through collective agency.