Sellers was a long-time librarian at Dickinson College and also held positions at Wesleyan University and the Winterthur Museum, Garden and Library.

[5] Sellers worked as a writer and researcher from 1927 and, together with his wife, owned and operated Tracey's Book Store in Hebron, Connecticut, from 1932 to 1938.

He also became the librarian in charge of the Waldron Phoenix Belknap Jr. Research Library of American Painting at the Winterthur Museum, Garden and Library, organizing this newly established collection and editing and publishing Belknap's research notes between 1956 and 1959.

With the opening of the May Morris Room in the new Boyd Lee Spahr Library, Sellers once again became historian and curator of the Dickinsoniana Collection in 1968.

[8] On October 6, 1932, Sellers married actor and poet Helen Earle Gilbert (died February 1951).