This chapter provides an overview of the critical factors involved in QoS. It also highlights all the key components that need to be analyzed for security and reliability and benchmarked for performance. Most of the discussion on standards is Web services (WS) focused for obvious reasons. Security, reliability, and performance should not be added as afterthoughts. Please consider analyzing carefully the QoS features of the components and how they map to one another, especially over extended enterprises. Furthermore, it is essential to have built-in redundancies and replications in the deployment of service infrastructures. This chapter does not cover redundancy issues in detail, even though they are alluded to. The QoS considerations discussed here should be developed in conjunction with overall recovery, non-interruption of production or service, and built-in redundancy solutions.