The Reagan Administration determined that the harm caused by UNESCO’s guiding leftist philosophy and endemic mismanagement problems outweighed the benefits of membership. As a result, President Reagan notified UNESCO in December 1983 that the United States would withdraw the following year...
September 16, 2002
George W. Bush In an otherwise excellent speech at the UN on September 12, President Bush, perhaps as a sop to win UN favor for military action in Iraq, called for the U.S. to rejoin the United Nations Education, Scientific, and Cultural Organization (UNESCO).
My guess is George's liberal wife, with her background and faith in public education, had much to do with George deciding to rejoining UNESCO.