Alfred Bloom says he will leave the post on Aug. 31, 2009.
Bloom has led the elite liberal arts school since 1991. He says a search committee will be formed in the coming weeks to select his successor.
School officials say that under Bloom's leadership Swarthmore has revitalized its honors program, renovated and built academic buildings, broadened its multicultural curriculum and expanded foreign study.
In announcing his departure Friday, Bloom said he has "held the dream job in American education for 17 years."
Swarthmore is located in the Philadelphia suburbs and has about 1,500 students.
