Web Services is an XML-based technology that has attracted significant attention for building distributed Internet services. Considerable research efforts have been trying to extend it to become a unifying management technology; initial evaluation efforts have demonstrated promising application potential in the domain of network and service management. This paper analyzes the monitoring requirements of a management system used in architectures for providing quality of service, and shows how Web Services can be used effectively to fulfill these requirements. In order to achieve this, a WS-based framework was designed and a query tool was developed to support distributed, optimized retrieval of management information exposed as Web Services. The query tool supports selective and bulk retrieval from MPLS-capable routers. Management information retrieval is demonstrated through three monitoring scenarios, and the measured performance in terms of latency and bandwidth is compared against a conventional approach based on SNMP.