The 9/11 Commission Report, officially called the Final Report of the National Commission on Terrorist Attacks Upon the United States, is the U.S. government-ordered report of the events surrounding the attacks of September 11, 2001. The commission began its investigation on November 26, 2002 and issued the report almost 20 months later, on July 22, 2004.
To reach its findings, the commission reviewed over 2.5 million documents and interviewed more than 1,200 people in ten countries. The final report has been frequently criticized for failing to provide sound analysis and recommendations. Oddly, however, it was widely praised as great reading, rising to the top of several bestseller lists. The National Book Foundation named the report as a 2004 National Book Awards finalist in the nonfiction category.
You can get the full text of the 9/11 Commission Report from CyberCemetery at http://govinfo.library.unt.edu, an archive of government websites that have ceased operation. CyberCemetery is run by the University of North Texas Libraries and the U.S. Government Printing Office.