Family and general correspondence, diaries, journals, notebooks, subject files, writings and speeches, financial papers, reports, biographical materials, scrapbooks, clippings, and other papers relating principally to Barrett's career as a journalist in California, Washington, and Oregon; his appointments as U.S. minister to Argentina, Colombia, Panama, and Thailand; his duties as director general of the Pan American Union; and his work as a counselor and arbiter in the area of Pan American commercial relations. Other topics include Barrett's travels in East Asia, his duties as special adviser to Admiral George Dewey during the Philippine Insurrection, the Venezuelan boundary dispute, the Panama Canal, and the general area of relations between the U.S. and Latin America.