This study examines concerns raised by the U.S. Department of Energy (DOE) in its planning for transition from active waste site management and remediation to what the department terms “long-term stewardship.” It examines the scientific, technical, and organizational capabilities and limitations that must be taken into account in planning for the long-term institutional management of the department’s numerous waste sites that are the legacy to this country’s nuclear weapons program. It also identifies characteristics and design criteria for effective longterm institutional management.