For social animals, group living can serve to buffer against stressors. However, changes in the social environment may also represent stressors, and social conditions have been linked to changes in glucocorticoids in many taxa. We studied glucocorticoids in captive bonobos (Pan paniscus), a social species with complex social organization. We sought to understand how bonobo individuals respond to changes in their social environment, and how these responses differ with dominance rank. We monitored bonobos before, during, and after a change occurred in their social environment, where a new group member was introduced at the captive facility. We repeatedly sampled individuals’ cortisol (corrected for creatinine) from urine samples using enzyme immunoassays. Using these results, we will investigate whether changes in cortisol concentrations occurred during the introduction of the new group member. Results from this study will provide insight into how bonobos respond to changes in group dynamics. This work is also important to inform animal welfare and management practices, where changes in social dynamics can be driven by caretakers rather than initiated by animals in the social group.