In 1921, Paterson became an assistant to Burton Rascoe, the new literary editor of the "New York Tribune", later the "New York Herald Tribune". For 25 years, from 1924 to 1949, she wrote a column (signed "I.M.P.") for the "Herald Tribune's" "Books" section. Paterson became one of the most influential literary critics of her time. She covered a time of great expansion in the United States literary world, with new work by the rising generation of Ernest Hemingway, F. Scott Fitzgerald and many others, African Americans of the Harlem Renaissance, as well as the first American generation of the great waves of European immigrants. Her friends during this period included the famous humorist Will Cuppy. In 1928 she became an American citizen, at the age of 42.