Dedicated servers remain to be a common constituent of Grid job scheduling architectures, forcing site administrators to make compromises between administrative expenses and system reliability. Apart from requiring administrative attention, dedicated servers create single points of failure and should not be subjected to network churn. This paper presents the design and implementation of Omnivore, a fully decentralized job scheduling system, built??on a peer-to-peer based meta-scheduler. Omnivore is able to cope both with node failures and network churn, eliminating the need for central administration and continuous resource availability. It is integrated into the Grid landscape (especially the Globus Toolkit 4) by means of the GridWay meta-scheduler toprovide scalable distributed scheduling, replicated storage and system monitoring capabilities. Results obtained from an experimental evaluation of our implementation show that Omnivore is both scalable and resilient in the presence of node failures and network churn.