The relationship between environmental uncertainty (EU) and interorganizational information sharing (IIS) remains equivocal. Existing research has investigated the phenomenon from only one partner’s perspective, based on either resource dependence theory (RDT) or transaction cost economics (TCE). This study assesses the relative strengths of RDT and TCE simultaneously by accommodating both partners’ perspectives in the same dyad. Our results show that TCE has greater explanatory power for the manufacturer position, but not for the supplier. Supplier EU does not influence supplier information sharing. RDT arguments are not fully supported for the whole paths. Interestingly, supplier EU influences joint dependence negatively.