2020). Legitimacy and relevance of a performance measurement system in a Finnish public-sector case. Abstract PurposeWe investigate the difficulties involved in translating stakeholder expectations into action and maintaining legitimacy through the use of a performance measurement system (PMS) created in a Finnish regional development company (RDC). This longitudinal case study illustrates the fluctuating and socially constructed nature of legitimacy in the public sector. Design/methodology/approachThis qualitative case study longitudinally analyzes the various developments occurring during and after the development of a PMS system for the case organization. Empirical data include interviews, workshops, observation, and other materials relating to the case organization. FindingsThe initial interest in operational improvement changed to legitimation-seeking behavior by the case organization when the measures created were modified to accord with the changed preferences of the key stakeholders. However, the pursuit of legitimacy for the RDC was made difficult by the outcome oriented, changing, and contradictory nature of stakeholders' demands. Our findings reveal a continuous mismatch between organizational activities and the board's expectations, leading to the eventual closure of the organization. Practical implicationsThe findings help to analyze the legitimacy and relevance of PMSs in public-sector projects. The study highlights the practical importance of analyzing the different legitimacy priorities of various stakeholder groups, such as politicians and entrepreneurs. Originality/valueThe study analyzes fluctuating nature of legitimacy longitudinally in the public-sector context from the stakeholder perspective. This study analyses a situation where the stakeholders' evaluations of the legitimacy of the organization, and the PMS developed, change over time, complicating the accounting for stakeholders.