Correspondence, artist files and subject files relate to Oakley's activities as an artist and illustrator, and his involvement with numerous art organizations, including the Philadelphia Art Alliance, the Philadelphia Water Color Club, the Artists' War Relief Committee of Philadelphia, and the Exposition of Indian Tribal Arts. Artist files on Cecilia Beaux, Florence Este, John Taylor Arms, John McLure Hamilton, Christian Brinton, George Morrow, Leila Mechlin, John Harkrider, Alexander Robinson, and Joseph Pennell, among others, primarily contain letters. Some also include photographs and printed matter. Four inches of letters from Beaux discuss working habits, portrait commissions, life in Paris, and personal matters. Letters from Este discuss life in France during the war, French artists, exhibitions at the Philadelphia Water Color Club, and Cecilia Beaux. Other material relates to Oakley's mural for the Franklin Institute.
