Social interactions are a ubiquitous part of human life. They are also complex and dynamic, posing a challenge for traditional psychology methods. This paper provides an overview of a dynamical systems approach to the study of social interactions that manages this complexity and enables the quantification of interdependence between people. We also discuss key empirical findings that demonstrate how different forms of interdependence and interaction dynamics shape social outcomes. Finally, we highlight the utility of this approach for advancing theories of social behavior and practical application. By adopting this dynamical systems approach, researchers can gain a deeper understanding of the patterns underlying social interactions and test hypotheses about the mechanisms driving human connection and coordination.