The US Army Corps of Engineers’ program that regulates filling of wetlands needs to be improved to meet the goal of no net loss of wetland area and ecological function, according to the National Academies’ National Research Counci! committee’s June 2001 report. The 13 committee members were charged with examining compensatory mitigation under section 404 of the Clean Water Act. We were asked to evaluate the degree to which the current mitigation program is restoring the structure and function of wetlands lost through development. We also were asked to evaluate the set of available options for mitigating wetland loss, including individual-permitee projects, mitigation banks, and in-lieu-fee programs. Hence, we examined both the science behind wetland restoration and mitigation institutions. The committee met five times in 2000, heard public testimony, listened to experts from around the country, and visited mitigation sites in Florida, Illinois, and California, before drawing its conclusions and making recommendations for improving compensatory mitigation efforts.