<p>Rumination is a core transdiagnostic factor underlying mental health, traditionally conceptualized as a maladaptive intrapersonal habit. However, rumination is deeply embedded in people’s relationships. Here we propose the Dynamic Interpersonal Model of Rumination (DIM-Rum), repositioning rumination as a recursive interpersonal, dynamic process. We start by outlining the traditional approach to rumination, and then integrate findings from diverse research areas to show how rumination is continuously shaped by and shaping the interpersonal world. Next, we present DIM-Rum, which complements and extends existing intrapersonal models by explicitly incorporating dynamic interpersonal feedback loops. We suggest implications and future directions that require the expansion of current methods and collaborations. By considering rumination in its interpersonal context, DIM-Rum offers novel targets for research and intervention.</p>