The Diaries describe Baker's growth as a collector of post-World War II art in New York, and his relationships with various artists, including Enrico Donati, Pierre Dumont, Jackson Pollock, Robert Motherwell, Richard Stankiewicz; dealers including Leo Castelli, Rose Fried, Sidney Janis; and New York society, including Sam and Jane Kootz, and the Walter Hochschilds, among others. He also details his relationship with The Museum of Modern Art including individuals such as Margaret Scolari Barr (Mrs. Alfred H. Barr, Jr.), Dorothy Miller, and Abe Chanin, among others.