Cohen served as an editor for several publishers over the years, including his own. After working as an editor for World Publishing, he was hired by Holt, Rinehart & Winston in 1961 as "religious-books editor," and then became editor-in-chief in 1964. In addition to his publishing and editing work, Cohen collected rare books. He and his wife founded an antiquarian bookstore named Ex Libris in 1973, which "specialized in books and documents of twentieth-century art, particularly Dada, Surrealism, and early Russian Constructivism." The business was initially run from their home, but by 1978 Ex Libris had been "moved to the ground floor of the Upper East Side Manhattan townhouse where the couple lived." Elaine finally closed Ex Libris in 1998.