William Schuman and Leonard Bernstein met at a Boston train station in February 1939, when the Harvard student was tasked with picking up the Sarah Lawrence professor whose Second Symphony was being performed by the Boston Symphony Orchestra that month. Over the next half-century, their bromance would blossom into a mutual admiration society and support system. The humour, warmth, lavish praise, and generous affection each man shared with the other fills the correspondence between the two, which comprises more than 100 letters, postcards, telegrams, and speeches, dating from 1939 to 1990, that are preserved among Schuman’s papers at the New York Public Library, Bernstein’s papers at the Library of Congress, and various other archives and libraries. This chapter provides an overview of these documents and showcases the importance of William Schuman in the professional and personal life of Leonard Bernstein.