One of the potential negative effects of online courses is a loss of social relationships and a loss of the sense of community that is usually present on a traditional campus. This paper presents evidence that collaborative learning strategies, which require relatively small classes or groups actively mentored by an instructor, are necessary in order for World Wide Web-based courses to be as effective as traditional classroom courses. The nature of collaborative learning versus other models, as well as some of the issues raised by Web-mediated education are reviewed. Results of recent studies at the New Jersey Institute of Technology and Penn State, indicating that collaborative learning is important to the success of asynchronous learning networks (ALNs) in creating positive outcomes for students, are summarized. The paper concludes that the question of how to build and sustain online learning communities is a prime area where researchers on ALNs ought to be focusing their efforts. (Contains 13 references.) (Author/AEF)