Between 1979 and 1984, Central Intelligence Agency (CIA) staff historian Jack Pfeiffer prepared five volumes of the Agency's Official History of the Bay of Pigs Operation. The titles of the first four volumes were Air Operations, March 1960-April 1961; Participation in the Conduct of Foreign Policy; Evolution of CIA's Anti-Castro Policies, 1951-January 1961; and The Taylor Committee Investigation of the Bay of Pigs. All have been declassified and are available to the public on CIA's website in the electronic reading room. Pfeiffer also wrote a draft fifth volume, CIA's Internal Investigation of the Bay of Pigs, being released today, which the CIA Chief Historian rejected as inadequate at the time, instructing Pfeiffer to make substantial revisions. Pfeiffer did not complete those revisions before retiring in 1984. Unlike his four other histories, this fifth draft volume was not publishable in its present form, in the judgment of CIA Chief Historians as well as other reviewers, because of serious shortcomings in scholarship, its polemical tone, and its failure to add significantly to an understanding of the controversy over the Bay of Pigs operation-much of which has now been discussed in open source histories and memoirs. CIA's Chief Historians have assessed that addressing those deficiencies would have required much more effort than the draft volume's potential value would justify. Consequently, it remains an unfinished and unpublished draft. In the attached draft volume, Pfeiffer took very strong issue with the findings of the CIA Inspector General, Lyman Kirkpatrick, who blamed the Bay of Pigs debacle on the Agency task force in charge of an operation that Kirkpatrick assessed was misconceived, mismanaged, and bound to fail from the outset. Kirkpatrick's report evoked a fervent defense from CIA's operations directorate (both of those documents have been declassified and are on CIA's website in the electronic reading room), and Pfeiffer in large part accepted the operations directorate's viewpoint. He contended that Kirkpatrick, for a variety of motives, conducted his inquiry from the start with the purpose of laying responsibility for the Bay of Pigs fiasco on the officers who planned and ran the operation and on two Agency leaders, Deputy Director for Plans Richard Bissell and DCI Allen Dulles. We are releasing this draft volume today because recent 2016 changes in the Freedom of Information Act (FOIA) requires us to release some drafts that are responsive to FOIA requests if they are more than 25 years old. David S. Robarge CIA Chief Historian, 2005 - present