Contamination by chemicals and radionuclides is being cleaned up at hundreds of sites around the US. While Federal, state, and local agencies, as well as various NGOs and private parties, are moving ahead with clean-ups of many sites, oftentimes, cleanup does not mean that all contaminants have been removed. When residual contamination remains mechanisms must be established for longterm institutional management (also called longterm stewardship) of the remaining contaminants and of the systems put in place to contain them. They may involve a combination of engineering controls, such as physical barriers intended to prevent contaminant migration or intrusion, and institutional controls, such as restriction of development or public access to contain or prevent exposures to residual contamination.  The need for longterm stewardship (LTS) of sites is widespread. However, analytic frameworks for designing and sustaining LTS systems are lacking, and efforts must draw on models and frameworks from other contexts. This Professional Development Fellowship will promote development of knowledge to support improvements in practical applications of LTS systems.  Research conducted by Tuler as part of the Fellowship will explore perspectives about a) LTS system requirements for anticipating, recognizing, and responding to failures of engineering and institutional controls and b) the role of public participation to achieve these functions.  Tuler will also compare the ways in which their perspectives reflect analytical propositions about creating and sustaining resource and hazard management institutions over ling periods of time.  Four streams of research will be mined to identify propositions for creating and sustaining LTS systems: high reliability organizations, adaptive management, risk governance, and common-pool resources.