Presidential and congressional investigations are particularly powerful tools for asking tough questions about highly visible, often complex government breakdowns. In this insightful work, Paul Light, one of America's premier authorities on public service and management, provides a deep assessment of what he has identified as the federal government's one hundred most significant investigations since World War II. The findings and impact of Light's top one hundred vary nearly as much as the rangeof topics they covered, including communist infiltration of government and the Sputniklaunch during the 1950s, the Ku Klux Klan and Vietnam War during the 1960s; Watergateand Central Intelligence Agency abuses during the 1970s; the Social Security crisis, Challenger disaster, and the Iran-Contra scheme during the 1980s; the back-to-backsieges at Waco and Ruby Ridge and Bill Clinton's impeachment in the 1990s; and the9/11 attacks, collapse of Enron, and the financial meltdown in the 2000s. Government's Greatest Investigationsprovides a deep history and analysis of these investigations, providing rare insight into why some great investigations succeeded, while others failed, and what investigators can do to increase the odds that their work will pay off in improved government performance and more effective public policy. Informed by a deep reading of investigatory histories, numerous interviews with legislators, commission members, and leading scholars, as well as his own experienceand original research, Light undertakes his own search for answers to a long list ofquestions about how each of these investigations performed. Was the investigationvisible and well led? Was it serious and thorough? Did it involve a particularlycontroversial issue or a powerful public figure? Were investigators given enoughfreedom to pursue their goals? Did they forge the bipartisanship so often associatedwith what he calls the "good investigation?" And most important, what are the mostimportant drivers of ultimate impact? Light's analysis will inform practitioners andobservers of government on what drives impact in the American system.