This book constitutes the refereed proceedings of the 4th International Workshop on Internet and Network Economics, WINE 2008, held in Shanghai, China, in December 2008. The 68 revised full papers presented together with 10 invited talks were carefully reviewed and selected from 126 submissions. The papers are organized in topical sections on market equilibrium, congestion games, information markets, nash equilibrium, network games, solution concepts, algorithms and optimization, mechanism design, equilibrium, online advertisement, sponsored search auctions, and voting problems.