The long-term performance of NPOs is based on their ability to link and maximize social value as defined in their mission. This involves legitimacy obtained from stakeholders influenced by and influencing NPO activities, and their operational capacity or economic efficiency. Thus, NPOs have to utilize multiple level accountability systems which should be compatible with their multiple objectives and stakeholders' claims. The accountability system of an NPO should focus on its operational capacity, because in order to maximize its efficiency, an NPO has to measure its resource use, cost structure, and financial structure. Legitimacy obtained from stakeholders is also integral. If an organization is considered a social contract between multiple stakeholders, it has to consider the social economic effects of its activities and it has the duty to account for them. However, since the mission of an NPO is to create and distribute social value to a certain specific group, its social value creation has the most important role and an NPO should measure the social value it has created. This article analyzes the accountability system of a specific type of Italian NPO called Centri di Servizio per il Volontariato (CSVs)-namely centers which provide services for voluntary associations. The aim of the research is to verify if the accountability system adopted by CSVs satisfies their need for multiple level information (operational, legitimacy, and social value) and accomplishes their stakeholder claims, and to determine its impact on the definition and implementation of their strategy and on their long-term performance. The research was carried out using the action research model, and the findings are based on the analysis of a sample of 64 CSVs situated throughout Italy.