How do social connections and the shared norms that arise from them shape health and behavior—and how can we leverage these forces to improve wellbeing? In this talk, I will discuss a series of field-based studies exploring social networks and norms as root drivers of human behavior and wellbeing. Drawing on ongoing research conducted in the United States and in rural Uganda, I will highlight how misperceived peer norms around HIV prevention, substance use, and violence can serve as entry points for novel strategies to promote health. I will also discuss longitudinal and intervention studies that use social networks and positive norms to foster behavior change. Specifically, in Uganda, we will identify and engage adolescents and young adults within secondary school networks to reduce peer norm misperceptions and accelerate the spread of HIV prevention practices. In U.S. barbershops, we have trained barbers as men’s health ambassadors and partner with them to shift norms around sexual health and HIV prevention uptake in Black communities. In Tennessee, our team’s work on residential mobility integrates geospatial mapping, geobiographic narratives, and socio-behavioral data to understand how networks, norms, and contexts shape engagement in HIV care. Together, these projects demonstrate how integrating frameworks from public health, sociology, and psychology with community-based fieldwork can inform interventions and policies that leverage social influence for social good.