—The article presents an approach to the development of multi-attribute decision making model that is based on DEX, an expert system shell for multi-attribute decision support. We demonstrate the applicability and flexibility of the approach presenting application of DEX in e-learning: assessment and evaluation of Learning Management Systems (LMS) where several conflicting objectives, like environmental, social and economic impacts, must be simultaneously taken into account. Decision analysis methodology can be of major assistance in tackling this kind of problem and has become the basis for developing and implementing better and better decision support models to try to overcome the increasing difficulties involved in complex decision making problems. With the multi-attribute decision making model, we illustrate its usefulness by showing its main features and its application to the above intervention problem.