This research investigates the conditions under which inequity in a buyer–supplier relationship influences a supplier's resource sharing with its buyer. More specifically, the authors examine the effects of both positive inequity and negative inequity under varying levels of interdependence magnitude and relative dependence. They further examine the effect of inequity on perceived relationship performance. The study includes a longitudinal survey design, with perceived relationship performance reported by a second informant. The study, conducted within the context of Japanese suppliers reporting on their relationship with U.S. buyers, takes a nuanced view of both inequity and relative dependence by employing spline variables to disentangle potentially different effects of positive and negative inequity and relative dependence of the supplier and buyer, respectively. The results reveal that firms' reactions to positive and negative inequity vary depending on the nature of the interdependence structure and that positive and negative inequity differentially influence perceived relationship performance. The findings are important for both further research and managerial action.