In this monograph we begin by situating the technological and historical origins of the World Wide Web in hypermedia systems that were conceptualized during the World War II era and first developed decades before the Web. We then review the cross-disciplinary theoretical and empirical literature on the uses and effects of educational hypermedia. This literature is spread across fields as diverse as cognitive and educational psychology, geography, educational technology, engineering, environmental psychology, and computer science. From this literature we specifically focus on: (1) hypermedia theory applicable to educational uses and effects of the World Wide Web, (2) empirical research on how individuals use hypermedia systems; and (3) empirical research on the cognitive effects of hypermedia systems. We conclude by discussing the implications of this theory and research in an effort to provide a framework for research on formal and informal learning via the World Wide Web. (Contains 118 references.) (Author)