The evolving needs of conducting commerce using the Internet requires more than just network quality of service (QoS) mechanisms for differentiated services. Empirical evidence suggests that overloaded servers can have significant impact on user perceived response times. Furthermore, FIFO scheduling done by servers can eliminate any QoS improvements made by network differentiated services. Consequently, Server QoS is a key component in delivering end to end predictable and stable services to end users. In my talk I will describe our research and results for WebQoS an architecture for supporting server QoS. We demonstrate that through content adaptation, classification, admission control, and scheduling we can support distinct performance levels for different classes of users and maintain predictable performance even when the server is subjected to a client request rate that is several times greater than the server's maximum processing rate. Our technique is to allocate server resources based on class of service to obtain performance isolation between co-hosted web sites and guaranteed performance differentiation between classes of clients.