This paper describes the architecture and discusses implementation issues of a scalable Internet-based teaching and learning system (SKILL) being developed at the University of Essen (Germany). The primary objective of SKILL is to cope with the different knowledge levels and learning preferences of the students, providing them with a collaborative and adaptive learning environment utilizing new World Wide Web technologies. Basic components of SKILL are course material based on concepts organized in an ordinal rating derived from pre-requirements, an annotation facility suited for collaboration work, and a configuration environment for tailoring the system. Topics discussed include: (1) SKILL functionality, including adaptivity/progress control and collaborativity through annotations and course extensions; (2) components, including security, document management, and tutoring components; (3) implementation issues; and (4) related work. A figure presents course refinement levels. Contains 13 references. (Author/AEF)