Interest in Grid computing has grown significantly over the past five years. Management of distributed cluster resources is a key issue in Grid computing. Central to management of resources is the effectiveness of resource allocation, as it determines the overall utility of the system. In this paper, we propose a new Grid system that consists of Grid Federation Agents which couple together distributed cluster resources to enable a cooperative environment. The agents use a computational economy methodology, that facilitates QoS scheduling, with a cost-time scheduling heuristic based on a scalable, shared federation directory. We show by simulation, while some users that are local to popular resources can experience higher cost and/or longer delays, the overall users’ QoS demands across the federation are better met. Also, the federation’s average case message passing complexity is seen to be scalable, though some jobs in the system may lead to large numbers of messages before bei...