As “market referees”, regulators contribute to the delivery of essential public services. Their organisational culture, behaviour and governance are important factors in how regulators, and the sectors they oversee, perform. The OECD Performance Assessment Framework for Economic Regulators (PAFER) looks at the institutions, processes and practices that can create an organisational culture of performance and results. The report uses PAFER to assess elements linked to both the internal and external governance of Peru’s Water and Sanitation Services Regulator (Superintendencia Nacional de Servicios de Saneamiento, Sunass). The review acknowledges the technical expertise of Sunass within the institutional framework, analyses the key drivers of its performance, and identifies a number of opportunities to help the regulator prepare for the future, including in the context of sector-wide challenges and the COVID-19 crisis.