The design of an Intelligent Web-based Interactive Language Learning (IWiLL) system to support English learning on the Internet is described. We designed two kinds of learning environments: 1) an interactive English writing environment; and 2) an authentic conversation learning environment. These are intended to improve learners' basic language skills in listening, reading, speaking, and writing. In addition, the system also offers authoring tools that facilitate teachers' content preparation. The system not only provides multimedia learning environments for users, but also builds a learner corpus, an archive of English texts written by learners for whom English is a second language. Further analysis of the learner corpus creates the potential to detect the users' persistent errors and then to provide adequate help to the users. An important aspect of the system is the careful integration of the multimedia environments in ways that systematically enrich the learners exposure to and grasp of specific aspects of the target language. For example, particular targeted vocabulary items can be encountered in text as well as video. The system also is designed to track a variety of facets of each learner's interaction with the environment. This tracked data in turn supports spiraling of English material that the learner has encountered.