The main purpose of e-learning systems is to provide learning materials through Internet to let learners upgrade their knowledge. To be more efficient, these systems must be able to present their learning materials based on learners' acquired knowledge as well as their learning capabilities (learning styles). Therefore, their development should be based on pedagogical models that make them able to adapt their learning materials on the bases of learners' competences (acquired knowledge and learning capabilities). This paper proposes a model and architecture of a learning system able to support pedagogical concepts such as learning styles and pre-requisite competences to adapt learning materials to learners based on their profiles.