Building on recent theoretical work documenting that interorganizational relationships (IORs) are 'multifaceted and multiplex' we investigate, from the agent's perspective, the joint effects of trust and opportunism in fostering (or inhibiting) relationalism, which, in turn, is predicted to influence performance within interfirm exchange relationships. Based on longitudinal survey data on 409 catalog intermediaries affiliated with a large retail firm, we found strong support for most of the hypothesized relationships. Implications for future research are offered.