Autograph manuscript poems of American historian and writer, William Roscoe Thayer.

Correspondence and manuscripts of poems of American biographer and historian William Roscoe Thayer.

Manuscripts of works by American biographer and historian William Roscoe Thayer.

Letters, compositions, and other papers of the American historian William Roscoe Thayer. Also includes miscellaneous papers of the American writer William Warland Clapp and the American abolitionist and writer Thomas Wentworth Higginson.

Correspondence and reviews concerning Thayer's biography of TR published in 1919; with a series of extracts of TR quotations arranged in broad categories, possibly for an anthology.