This edited book is intended to be a companion volume to our Handbook on Electricity Markets (Glachant, Joskow, and Pollitt, 2021). That book focused on wholesale electricity markets, looking at how these had evolved over time, and how they were being changed by the addition of significant quantities of intermittent renewable electricity to the generation mix. We also looked at the operation of the electricity market in developing countries. This book turns the focus to the formally regulated parts of the electricity sector, focusing on network regulation, the role of economic regulators, and the regulation of retail electricity. We have divided the book into three parts: the first focuses on where we are now; the second on where we are going; and the third on non-OECD countries. Parts I and II focus on the United States (US), Great Britain (GB), Australia, and the European Union (EU) as this is where the oldest and most sophisticated economic regulation of electricity has emerged. Part III turns its attention to developments in India, China, and lower- and middle-income countries (LMICs) more generally.