This article discusses an 8-year, ongoing project that evaluates the Environmental Protection Agency's Superfund community involvement program. The project originated as a response to the Government Performance and Results Act, which requires federal agencies to articulate program goals, and evaluate and report their progress in meeting those goals. The evaluation project assesses how effective the Superfund community involvement program is in promoting public participation in decisions about how to clean up hazardous wastes at Superfund sites. We do three things in the article: (1) share our experience with evaluating an Agency public participation program, including lessons learned about methods of evaluation; (2) report evaluation results; and (3) address a number of issues pertaining to the evaluation of public participation in environmental decision-making. Our goal is to encourage more environmental managers to incorporate evaluation into their public participation programs as a tool for improving them. We found that written mail surveys were an effective and economical tool for obtaining feedback on EPA's community involvement program at Superfund sites. The evaluation focused on four criteria: citizen satisfaction with EPA information about the Superfund site, citizen understanding of environmental and human health risks associated with the site, citizen satisfaction with opportunities provided by EPA for community input, and citizen satisfaction with EPA's response to community input. While the evaluation results were mixed, in general, community members who were most informed about and involved in the cleanup process at Superfund sites generally were also the most satisfied with the community involvement process, and the job that EPA was doing cleaning up the site. We conclude that systematic evaluation provides meaningful and useful information that agencies can use to improve their public participation programs. However, there need to be institutionalized processes that ensure evaluation results are used to develop and implement strategies for improvement.