"The Puzzle Palace" has been generally well received by experts, and has been used as a textbook at the Defense Intelligence Agency's National Intelligence University. The NSA itself says the book "brought a new focus to the efforts of journalists and independent writers to break down the Agency's vaunted anonymity," and describes the book as "the most significant breach in NSA's anonymity since David Kahn's "The Codebreakers" in 1967." In the years between the book's publication and 9/11, the relationship between Bamford and the NSA grew less adversarial. The NSA cooperated with Bamford on a later book titled "Body of Secrets", and in April 2001 the NSA hosted a book-signing event for Bamford at their Maryland headquarters. Bamford was critical of NSA actions in the years following 9/11, and the relationship between the two once again cooled.