The Toronto-born Computer-Supported Intentional Learning Environment System (CSILE) is an advanced computer-supported cooperative learning system being developed at the Ontario Institute for Studies in Education. This system has been refined by working closely with teachers and students engaged in an educational approach called "knowledge-building." This paper explores the guiding principles of this approach: deep understanding through conflict between new knowledge and old preconceptions; scrupulously organized pursuit of understanding; knowledge in a social context; and knowledge building as a goal rather than an eventuality. Used with this approach, CSILE has demonstrably positive effects on standardized test scores and a variety of measures of deep understanding. Specific technical ways in which CSILE supports an information-sharing infrastructure tailored to this theory are discussed, including the ability to aggregate knowledge, to link pieces of knowledge, and to create integrated discussions. CSILE's capabilities are compared with the AppleShare fileserver. Reproductions of computer screens illustrate the discussion. (Contains 12 references.) (Author/BEW)