Utilizing the World Wide Web (Web) for delivering lifelong training services to individuals or communities raises great interest in intelligent methods for adaptive course curriculum building. People notice that it is insufficient to make training materials accessible by way of the browser. To satisfy learner requirements, the learning service has to give a highly customized and up-to-date view. Moreover, training is an interactive and collaborative process. The flow of the curriculum has to follow some didactic principles. Learners need to be guided through the training material according to these principles and their own preferences. A conventional hypertext system cannot provide this, mainly because the pedagogic semantics of the material are not “known” by the system. This article presents a new approach for adaptive, computer-supported learning services within our Lifelong Learning project. This approach is based on a formalization of pedagogical knowledge, about learning material and learning processes, as well as the domain knowledge and a learner model. The goal of our research is to integrate efficient and reusable pedagogical knowledge representations into an adaptive learning system (and authoring tools). The article concentrates on the Didactic Planning obtained by various Pedagogical Strategies. Therefore, we focus on the strategy formalization using an expressive knowledge representation based on a dedicated learning ontology using conceptual graphs. The power of our approach for designing a new kind of adaptive learning system is demonstrated through examples of pedagogical strategies applied to course material.