We describe the development of OpenACES, an enterprise level computer system for e- learning. OpenACES is an ongoing open source project to deliver a complete on-line training infrastructure that is scalable, robust, extendable and that contains a number of highly useful features. The software, now used to deliver all online courses at the Sloan School of Management (MIT), is widely used in other commercial and academic environments. In the first section of this report we comment on the aims for the software system and the problems it tries to solve. In the second part we discuss its teaching and learning functionalities as well as its technical requirements.