An active e-course is a self-representable and self-organizable document mechanism with a flexible structure. The kernel of the active e-course is to organize learning materials into a "concept space" rather than a "page space". Besides highly interactive service, it supports adaptive learning by dynamically selecting, organizing and presenting the learning materials for different students. During the learning progress, it also provides assessments on students' learning performances and gives suggestions to guide them in further learning. We have implemented an authoring tool and a course prototype to support the constructivist learning. Categories & Subject Descriptors: K.3.2 [Computers and Education]: Computer and Information Science Education ? computer science education, curriculum. General Terms: Management, Design, Human Factors.