Over the last years, online learning has gained significant popularity, and this trend is expected to continue in the future. Online learning is a multi-dimensional activity where each dimension should be adequately supported by an online learning system to provide a fruitful learning experience to its users. Similar to online learning, a particular approach in the way systems are designed has gained increasing popularity over the last years as a result of the emergence of the computer network. Systems have started to be envisioned as integrated collections of components that are deployed over the network. This network-centric approach addresses some of the issues that are not directly addressed by the traditional architectural design approaches. We believe that such an approach can be employed for the architectural design of online learning environments (OLEs) where different dimensions of online learning are addressed by different components residing on the network. This thesis presents a network-centric system architecture for OLEs. The architecture is based on the Service-Oriented Architecture (SOA) paradigm and web services. The proposed architecture is described using a number of Department of Defense Architecture Framework (DoDAF) representations. We also developed a quality model for OLEs and evaluated the architecture using this quality model. We believe that this research is an important first step in reconciling those two emerging ideas, namely online learning and network-centric architecture. This reconciliation is important as the flexible nature of SOA can be very useful in creating OLEs that address a wide variety of user needs. / Master of Science