What is personal space? It describes the “invisible bubble” immediately around an individual, where intrusion by others may feel uncomfortable or even threatening. Despite personal space being important for determining the size and dynamics of large groups and how animals behave, it is unknown how animals generate and maintain their sense of personal space. I explore this question using Drosophila flies, a powerful model system for studying behavior. Individual flies communicate via a large set of behaviors (e.g. kicking, flicking the wings, flying, and running) that can shape group interactions. Between pairs of flies, there is a rich repertoire of interactions that cause them to either move away (e.g. appendage touching) or move closer (e.g.courtship behaviors). To capture these behaviors, I use high resolution cameras running at 150 fps to collect videos of flies interacting in a circular arena and deep-learning software for annotating body parts (SLEAP). I use this data to track the poses of multiple flies throughout time and quantify appendage touching behaviors in addition to an estimate of each fly’s personal space. Using optogenetics, I model a situation in which a wild-type fly responds and adapts to being surrounded by other flies that crowd tightly. One expected outcome is that the wild-type fly will increase appendage touching in response to the space around itself shrinking. My goal is to determine exactly how the dynamics of such inter-fly interactions form a sense of personal space for each fly. My work will uncover the patterns of interactions that develop personal space and how these patterns scale out to larger social networks.