Regulators operate in a complex, high-risk environment at the interface between the public and the private sectors. They often share some responsibilities for the sectors and industries they regulate with other public institutions. And yet, if the lights go out, tap water stop running, trains break down or phones stop working, they are often held to account. In this challenging environment, the governance of regulators is critical. The role of the regulator and how it co-ordinates with other public institutions, the powers it is given and how it is held accountable for exercising these powers are key elements of a governance architecture that needs to be carefully crafted and appropriately implemented if the regulator is to succeed in combining effective regulation with a high level of trust. This report looks at the way in which four regulators – the Australian Competition and Consumer Commission (ACCC), the Australian Energy Regulator (AER), Portugal’s Water and Waste Services Regulation Authority (ERSAR) and the UK Office of Rail and Road (ORR) – have addressed these governance challenges. The report identifies approaches to implement accountability, transparency and co-ordination and helps identify some lessons that can help guide how these principles can be translated into practice.