This article discusses one of the main features of ICT—interactivity. Drawing from many years of Web-based course design and delivery at the University of Hong Kong, it is argued that enhanced interactivity is the single most important reason why teachers should practice Web-based teaching. The notion of conversational learning community (CLC) as a kind of constructivist learning environment is introduced. It is shown that instructional interactivity, defined as active communication in a conversational learning community between instructor(s), learners, course materials, and links to remote experts and resources, is a central aspect of the learning situation. A practical implementation of the CLC model is presented through describing the interactive features of a Web-based course using WebCT. It is concluded that Web-based teaching actually enhances interactivity both within and beyond the classroom setting.