Recent technological developments, including gigabit networking technology and low-cost, high-performance microprocessors, have given rise to metacomputing environments. Metacomputing environments combine hosts from multiple administrative domains via transnational and world-wide networks. Managing the resources in such a system is a complex task, but is necessary to efficiently and economically execute user programs. The Legion resource management system is flexible both in its support for system-level resource management but also in their adaptability for user-level scheduling policies.