The constitutive role of accounting, proposed in social studies of accounting, complicates the understanding of the relationship between organizational realities and accounting representations of organizations. Making this conflict an empirical question, the study attends to the ontological work in practices of representing organizational Performance in a boardroom. The study draws upon an ethnographic study of management and board work in a theatre company in 2010-2015. By attending particularly to the ontological work in accounting practices of knowing company performance, the aim of the paper is to contribute to the understanding of the role of accounting in the enactment of organizational realities. Findings illuminate how board practices of monitoring and reporting on Performance produce multiple ontologies of Performance. Rather than striving for commensuration or elimination of such differences, the theatre board organizes its practices to uphold multiple, ontologically different, versions of Performance. The study contributes to recent discussions on fluidity and ontological multiplicity in accounting practices, and the paper calls for further analysis of ontological compatibility between accounting technologies and the practices in which these are used.