This book provides a systematic overview of transmission network investment in liberalized power markets. Recent government policies to increase the share of intermittent renewable power generation and other technological innovations present new theoretical as well as practical challenges for transmission investments. Written by experts with a background in both economics and engineering, the book examines the economic and technical fundamentals of regulated and merchant transmission investment, and includes case studies of transmission investment in a number of countries. The book is divided into four parts: Part 1 introduces the basic economics and engineering of transmission network investment, while Part 2 discusses merchant investment in the transmission network. Part 3 then examines transmission investment coordination and smart grids, and lastly, Part 4 describes practical experiences of transmission network investment in power market in various countries.