Clergyman and pacifist. Diaries, correspondence, speeches and writings, and subject files pertaining to the career and activities of Frederick Joseph Libby, executive secretary of the National Council for Prevention of War.

Diplomat, publicist, civic leader, and peace advocate. Scrapbooks and correspondence relating to Marburg's civic activities in Baltimore, Maryland, his belief in internationalism and advocacy for peace before and after World War I, his role as United States minister to Belgium from 1912 to 1914, and his work as an art collector and public art advocate.

Civil rights activist and author. Correspondence, memoranda, speeches, notes, reports, press releases, financial records, agendas, printed material, and other papers documenting Bayard Rustin's leading role as an activist in the African American civil rights movement, advocate of international human rights and social reform, and pacifist.