Van Doren was dropped by NBC and resigned from his post as an English instructor at Columbia University. He became an editor at Praeger Books and a pseudonymous (at first) writer, before becoming an editor of the "Encyclopædia Britannica" and the author of several books, of which his 1991 popular-market "A History of Knowledge" may be his best known. Van Doren also co-authored a well-received revision of "How to Read a Book" with its original author, philosopher Mortimer J. Adler, and co-edited with him a 1,771-page anthology titled "Great Treasury of Western Thought" (1977). He had already worked with Adler on an 18-volume collection of documents covering American history, entitled "The Annals of America" (1968), which was accompanied by a two-volume, 1,300-page "topical index" organized around 25 themes and entitled "Great Issues in American Life: A Conspectus".