The Correspondence subseries is arranged by date and in one instance by topic. Pillsbury's correspondents include Henry F. Adams, Floyd Henry Allport, James R. Angell, George F. Arps, Henry M. Bates, Alfred Binet, Edwin G. Boring, Norman A. Cameron, James M. Cattell, Moses Gomberg, Wilbert B. Hinsdale, Percy Hughes, Clark L. Hull, Harry B. Hutchins, William James, Clarence T. Johnston, Charles H. Judd, Kurt Lewin, Norman Maier, Hugo Munsterberg, Carl Murchison, Carl Seashore, Edward Titchener, Edward C. Tolman, Howard C. Warren, Robert M. Wenley, Harry Wolfe, Lloyd S. Woodburne, Robert M. Yerkes, Clarence Yoakum, Robert S. Woodward, and Robert S. Woodworth. There are some family letters in this subseries, especially letters to his wife written while he was lecturing abroad, but the bulk of the letters among family members will be found in the Family Papers series.