Under increasing pressure to demonstrate environmental responsibility, organizations realize that they cannot claim to be environmentally sustainable if their supply chains are not. This research seeks to understand how an interorganizational green IS influences environmental sustainability (ES) initiatives within organizations in a supply chain. We examine a green IS taking the form of an interorganizational ES platform. Our analysis gives insight into how role conflicts arising from the various roles played by the platform users compromise the nature of actions associated with platform beliefs. In particular, cooptition conflict arising from participants’ roles as supplier to the platform owner and competitor to other platform participants explains the symbolic organizational content contribution, whereas the professional conflict resulting from participants’ roles as employee of an organization and knowledge peer to participants from other organizations explains the substantive personal content contribution. The lack of organizational substantive content creates content paucity, which platform users respond to by developing off-platform relationships with content contributors. The personal ES knowledge acquired through platform content consumption and the relationships with content contributors help individuals advocate for ES initiatives within their organizations. Our research is among the first to consider green IS at an interorganizational level and the corresponding multilevel perspective of the green IS users as they are at once organizational and individual actors.