Policy-based management was promoted as a solution to provide flexibility to dynamically assign network resources, control QoS and security, by means of administratively specified rules. Reality has showed that policy is a methodology hard to implement and has not yet been widespread used. In addition to policy conflict analysis, a key issue for this reticence is the need to derive enforceable policies from high-level administrative directives, namely the policy refinement problem. This book provides a holistic view of this process, from formal analysis to its practical realization, identifying the key elements involved in each step of such critical process. For instance this book proposes a refinement framework and advances the state of the art providing a methodology to address policy refinement in network management contexts. Finally, taking intra-domain Quality of Service Management as background domain this book presents the execution of a complete refinement process in an affo...