In the 1990s, the Environmental Protection Agency (EPA) increased its efforts to involve the public by giving citizens, industry, environmental groups, and academics a much greater opportunity to play key roles in environmental decision-making. Today, EPA is continuing this tradition by initiating and supporting a vast array of stakeholder involvement and public participation initiatives well beyond the scope of what was originally in place when the Agency opened for business in 1970. With this report, the Office of Environmental Policy Innovation (OEPI) has taken a fresh look at Agency efforts to involve the public by reviewing formal evaluations and informal summaries from across the Agency that identify, describe, and/or evaluate Agency stakeholder involvement and public participation activities. Based upon our review, we identify key crosscutting lessons learned, pinpoint unique barriers and ways to overcome them, and highlight innovative approaches to stakeholder involvement and public participation. This report is informed by Agency evaluations and reviews and is written for Agency staff and EPA's co-regulators. As such, it will be a valuable tool for staff who are (1) considering new initiatives; (2) seeking to improve existing ones; or (3) in need of new perspectives on stakeholder involvement and public participation at the Agency.