Owing to its procedural mission and the specific characteristics of rights protection organizations, the evaluation of an Ombudsman's performance is a complex task. This article presents a knowledge synthesis of performance measurement for Ombudsman's Offices and opens the way to new reflections that are both theoretical and practical. In addition to presenting the strengths and weaknesses of the various evaluation models identified in the literature, this study clarifies the purpose of the Ombudsman and the purposes for which it is evaluated. Finally, this article formulates propositions for an integrated assessment of the management of the Parliamentary Ombudsman.