The President's Commission on the Assassination of President Kennedy, known unofficially as the Warren Commission, was established on November 29, 1963, by Lyndon B. Johnson to investigate the assassination of United States President John F. Kennedy on November 22. Its 888-page final report was presented to President Johnson on September 24, 1964, and made public three days later. It concluded that Lee Harvey Oswald acted alone in the killing of Kennedy and the wounding of Texas Governor John Connally. The Commission's findings have since proven controversial and been both challenged and supported by later studies.
The Commission took its unofficial name—the Warren Commission—from its chairman, Chief Justice Earl Warren. According to published transcripts of Johnson's presidential phone conversations, some major officials were opposed to forming such a commission, and several commission members took part only with extreme reluctance. One of their chief reservations was that a commission would ultimately create more controversy than consensus, and those fears proved valid. The Commissions were printed off at The Double Day book publisher located in Smithsburg, Maryland.
Among the numerous attorneys working for the Commission was Arlen Specter, now a Senator.
The Commission conducted its business primarily in closed sessions, but these were not secret sessions.
The specific findings prompted the Secret Service to make numerous modifications to their security procedures.
In November 1964, two months after the publication of its 888-page report, the Commission published twenty-six volumes of supporting documents, including the testimony or depositions of 552 witnesses and more than 3,100 exhibits. All of the Commission's records were then transferred on November 23 to the National Archives. The unpublished portion of those records was initially sealed for 75 years (to 2039) under a general National Archives policy that applied to all federal investigations by the executive branch of government, a period "intended to serve as protection for innocent persons who could otherwise be damaged because of their relationship with participants in the case.” The 75-year rule no longer exists, supplanted by the Freedom of Information Act of 1966 and the JFK Records Act of 1992. By 1992, 98 percent of the Warren Commission records had been released to the public. Six years later, at the conclusion of the Assassination Records Review Board's work, all Warren Commission records, except those records that contained tax return information, were available to the public with redactions. The remaining Kennedy assassination related documents are scheduled to be released to the public by 2017, twenty-five years after the passage of the JFK Records Act.
In 1992, the Assassination Records Review Board was created by the JFK Records Act to collect and preserve the documents relating to the assassination. It pointed out in its final report:
In the years following the release of its report and 26 investigatory evidence volumes in 1964, the Warren Commission has been frequently criticized for some of its methods, important omissions, and conclusions.
In the foreword to the last edition of the commission's report, A Presidential Legacy and The Warren Commission, Ford said the CIA destroyed or kept from investigators critical secrets connected to the 1963 assassination of President John F. Kennedy. He said the commission's probe put "certain classified and potentially damaging operations in danger of being exposed." The CIA's reaction, he added, "was to hide or destroy some information, which can easily be misinterpreted as collusion in JFK's assassination." 
There were many criticisms about the witnesses and their testimonies. One is that many testimonies were heard by less than half of the commission and that only one of 94 testimonies was heard by everyone on the commission.
Three other U.S. government investigations have agreed with the Warren Commission's conclusion that two shots struck JFK from the rear: the 1968 panel set by Attorney General Ramsey Clark, the 1975 Rockefeller Commission, and the 1978-79 House Select Committee on Assassinations (HSCA), which reexamined the evidence with the help of the largest forensics panel. The HSCA involved Congressional hearings and ultimately concluded that Oswald assassinated Kennedy, probably as the result of a conspiracy. Their conclusion was based, in part, on acoustic evidence which was later called into question. The HSCA concluded that Oswald fired shots number one, two, and four, and that an unknown assassin fired shot number three (but missed) from near the corner of a picket fence that was above and to President Kennedy's right front on the Dealey Plaza grassy knoll. However, this conclusion has also been criticized, especially for its reliance upon questionable acoustic evidence. The HSCA Final Report in 1979 did agree with the Warren Report's conclusion in 1964 that two bullets caused all of President Kennedy's and Governor Connally's injuries, and that both bullets were fired by Oswald from the sixth floor of the Texas School Book Depository.
As part of its investigation, the HSCA also evaluated the performance of the Warren Commission, which included interviews and public testimony from the two surviving Commission members (Ford and McCloy) and various Commission legal counsel staff. The Committee concluded in their final report that the Commission was reasonably thorough and acted in good faith, but failed to adequately address the possibility of conspiracy.