The rise of the "information society" offers not only considerable peril but also great promise Beset from all sides by a never-ending barrage of media, how can we ensure that the most accurate information emerges and is heeded? Cass R. Sunstein here develops a deeply optimistic understanding of the human potential to pool information, combat groupthink, and to use that knowledge to improve our lives. New ways, many Internet-based, to share and aggregate information--including wikis, open-source software, and prediction markets--are helping companies, schools, governments, and individuals not only to acquire, but also to create, ever-growing bodies of accurate knowledge without succumbing to the dangers of a hive-mind mentality. In a world where opinion and anecdote increasingly compete on equal footing with hard evidence, the on-line effort of many minds coming together could provide the best path to infotopia.