The ability to create virtual organisations (VOs) on demand in a dynamic, open and competitive environment is one of the challenges that underlie Grid computing and Web Services research. It is widely recognised that to form and manage a VO effectively, the ability to gauge quality of service (QoS) is important. Existing methods for managing QoS in SOC environments tend to adopt a provider-centric perspective, aiming largely at optimising and guaranteeing QoS for service delivery. In this paper we consider QoS management of VOs from a service user?s perspective, proposing techniques for supporting service users in assessment and monitoring of QoS during VO formation and operation.