This chapter describes and discusses the application of collaborative filtering techniques to the design of metadata structures for learning objects, and its implications for instruction. This approach enables context-sensitive discovery and recommendation of learning objects. The discussion is based upon research in developing and evaluating a collaborative filtering system, which enables users to share ratings, opinions, and recommendations about resources on the Web. An additional benefit of this approach is that it also allows a user to locate other users that share similar interests for further communication and collaboration.