Trust management is essential for secure node collaboration in ubiquitous computing environments for mission critical applications in military, crisis management, telemedicine and others. In this paper, we design and develop a novel hierarchical architecture called NeVo (Network of Volunteers) to facilitate trust management. The architecture uses a small subset of the nodes called volunteers to perform basic services such as resource provisioning, service discovery and mobility management in the network. The proposed mechanism operates autonomously through nodes’ cooperation. We choose service discovery to illustrate how the proposed trust management mechanism are accomplished through interactions among nodes. Simulation studies demonstrate that NeVo exhibits high efficiency and performance compared to existing distributed approaches in open pervasive environments.