This paper describes a dynamic, scalable and flexible Policy-based Management Architecture (PbMA), which is characterized by a reliable and autonomous deployment, activation and management of Grid Services. This architecture follows the implied conditions by the Open Grid Services Architecture (OGSA) standard. Although applicable to any user profiles, our system is essentially intended for non-massive resource owners accessing large amounts of computing, software, memory and storage resources. Unlike similar architectures, it is able to manage service requirements demanded by users, providers and services themselves. This architecture is also able to manage computational resources in order to fulfill Quality of Service (QoS) requirements, based on a balanced scheduling of resources exploitation. Our approach is scalable and flexible by extending itself the management components and policies interpreters needed to control multiple infrastructures regardless network technology, operative platform or administrative domain. The management architecture shows its reliability through a Grid Service deployment example.