Policy-based Management has been the subject of extensive research over the last decade.More recently, the IETF has been investigating Policy-based Networking as a means for managing IP-based multiservice networks with quality of service guarantees.P olicies are seen as a way to guide the behaviour of a network or distributed system through high-level, declarative directives.W e mainly view policies as a means of extending the logic of a management system at runtime, so that it can be adaptive to changing or newly emerging requirements.W e are interested in particular in the coexistence of hard-wired hierarchical management systems with policy logic in a fashion that the overall system becomes programmable and extensible.In this paper we consider generic issues behind hierarchical policy-based management systems and we present initial work on such a system for dimensioning and dynamic resource management in IP Differentiated Services networks.