The paper questions common assumptions in the dominant representational framings of information systems success and failure and proposes a performative perspective that conceives IS success and failure as relational effects performed by sociomaterial practices of IS project actor-networks of developers, managers, technologies, project documents, methodologies, and other actors. Drawing from a controversial case of a highly innovative information system in an insurance company—considered a success and failure at the same time— the paper reveals the inherent indeterminacy of IS success and failure and describes the mechanisms by which success and failure become performed and thus determined by sociomaterial practices. This is explained by exposing ontological politics in the reconfiguration and decomposition of the IS project actor-network and the emergence of different agencies of assessment that performed both different IS realities and competing IS assessments. The analysis shows that the IS project and the implemented system as objects of assessment are not given and fixed, but are performed by the agencies of assessment together with the assessment outcomes of success and failure. The paper demonstrates that by reframing IS success and failure, the performative perspective provides some novel and surprising insights that have a potential to change conversations on IS assessments in both the IS literature and IS practice.