First as a student, then as a friend and financial supporter, Forbes maintained a close relationship with the college for nearly two decades. His files of correspondence relating to the school include letters dating from 1937 to 1959 concerning administration of the college, faculty changes, campus and physical plant development, operating finances and issues relating to property owned by the college. Three of the letters provide interesting insights into two faculty members who subsequently attained a degree of celebrity in the field of literary criticism, Alfred Kazin (December 7, 1944, and June 20, 1945) and Eric Bentley (August 15 and December 7, 1944). Others of the letters provide substantive information on Anni Albers and her weaving room at the college (March 16, 1944), theater productions (April 22 and May 29, 1944), the Summer Music Institute (July 10, 1944), and efforts by the college to bring a degree of racial intergration into its programs (March 11, 1943, February 25, 1944, and April 22, 1944). Correspondents include Ted Dreier, William Robert ("Bob") Wunsch, Natalya ("Natasha") Goldowski, David H. Corkran, Dan Rice, Nell Aydelotte Rice, Frank Aydelotte, Toni Dehn, Flola Lake Shepard, Charles Olson, and Wesley Huss.

Other materials in the collection include pages from a journal kept by Forbes during a visit to the college, November 19-25, 1949; class notes and exams from the period when he was a student in 1935-1938; notes on the 1935 financial situation of the college; Howard Haines Brinton's ten drawn from his experience at the Quaker institution, Pendle Hill, in Pennsylvania; notes on the remarks of a labor operative from the United Mine Workers of America concerning unions and coal strikes of the 1930's; notes of the meeting held at the time of the visit of Louis Adamic to Black Mountain College in 1935; notes on other meetings held at the college between 1936 and 1941; and a 1941 at the college.