William Sims Bainbridge Virtual worlds are persistent online computer-generated environments where people can interact, whether for work or play, in a manner comparable to the real world. The most prominent current example is World of Warcraft (Corneliussen and Rettberg 2008), a massively multiplayer online game with 11 million s- scribers. Some other virtual worlds, notably Second Life (Rymaszewski et al. 2007), are not games at all, but Internet-based collaboration contexts in which people can create virtual objects, simulated architecture, and working groups. Although interest in virtual worlds has been growing for at least a dozen years, only today it is possible to bring together an international team of highly acc- plished authors to examine them with both care and excitement, employing a range of theories and methodologies to discover the principles that are making virtual worlds increasingly popular and may in future establish them as a major sector of human-centered computing.

New World View.- Culture and Creativity: World of Warcraft Modding in China and the US.- The Diasporic Game Community: Trans-Ludic Cultures and Latitudinal Research Across Multiple Games and Virtual Worlds.- Science, Technology, and Reality in The Matrix Online and Tabula Rasa.- Spore: Assessment of the Science in an Evolution-Oriented Game.- Medulla: A Cyberinfrastructure-Enabled Framework for Research, Teaching, and Learning with Virtual Worlds.- A Virtual Mars.- Opening the Metaverse.- A Typology of Ethnographic Scales for Virtual Worlds.- Massively Multiplayer Online Games as Living Laboratories: Opportunities and Pitfalls.- Examining Player Anger in World of Warcraft.- Dude Looks like a Lady: Gender Swapping in an Online Game.- Virtual Doppelgangers: Psychological Effects of Avatars Who Ignore Their Owners.- Speaking in Character: Voice Communication in Virtual Worlds.- What People Talk About in Virtual Worlds.- Changing the Rules: Social Architectures in Virtual Worlds.- Game-Based Virtual Worlds as Decentralized Virtual Activity Systems.- When Virtual Worlds Expand.- Cooperation, Coordination, and Trust in Virtual Teams: Insights from Virtual Games.- Virtual Worlds for Virtual Organizing.- Future Evolution of Virtual Worlds as Communication Environments.- The Future of Virtual Worlds.