His most notable work, The Land of Plenty, focuses on a lumber mill in a thinly disguised version of his hometown in Washington state.

[2] In 1919, the massacre during a strike in nearby Centralia, Washington, deeply disturbed him and left a lasting impression that appeared in his major writings.

[1][3] In 1929, after selling a short story "Hanging by My Thumbs" to The New American Caravan, he moved (with help from childhood friend Calvin Fixx) to New York City, landed a book contract with Farrar and Rinehart, and began work on his first novel, Laugh and Lie Down (1931).

In December 1933, he accepted work already passed over by Whittaker Chambers, namely to co-write a biography of Boston's E. A. Filene, in collaboration with Lincoln Steffens.

Throughout the 1930s, Cantwell began to meet New York writers and editors such as Edmund Wilson, Malcolm Cowley, John Chamberlain, Erskine Caldwell, Matthew Josephson, and Harry Hansen.

He worked on a number of articles, three of which became books: Alexander Wilson: Naturalist and Pioneer (1961), The Real McCoy (1971), and The Hidden Northwest (1972).

[1] They had three children: Joan[11] McNiece (Mrs. George Stolz, Jr.), Betsy Ann (Mrs. Walter Pusey III), and Mary Elizabeth Emmett (Mrs. Lars-Erik Nelson).

[1][2] He later married Allison Joy, a noted portrait painter, and, briefly, Eva Stolz Gilleran shortly before his death in 1978.

[citation needed] Cantwell was rumored to have been the inspiration for many of the scenes in the Eric Hodgins novel Mr. Blandings Builds His Dream House.

Biographer Per Seyersted concluded, "That Cantwell did not use correct Marxist terminology would seem to indicate that he was no CP member, that however to the left he was and in sympathy with the Party's aims, he was an independent person doing his own thinking.

He died in 1978, aged 70, in St. Luke's hospital in New York City, after suffering a heart attack two weeks earlier.

When Cantwell wrote of Banjo Paterson, the virtually unknown author of Waltzing Matilda, he made sure that a colorful footnote to history was not going to be lost, at least not to SI readers.

[1][13] F. Scott Fitzgerald wrote of Cantwell's first short story, "Hanging by My Thumbs": "Mark it well, for my guess is that he's learned a better lesson from Proust than Thornton Wilder did and has a destiny of no mean star.

Cantwell, his close colleagues, and many staff members as of the 1930s helped elevate Time–"interstitial intellectuals," as historian Robert Vanderlan has called them.

[14] Colleague John Hersey described them as follows: Time was in an interesting phase; an editor named Tom Matthews had gathered a brilliant group of writers, including James Agee, Robert Fitzgerald, Whittaker Chambers, Robert Cantwell, Louis Kronenberger, and Calvin Fixx...

Time's style was still very hokey—“backward ran sentences till reeled the mind”—but I could tell, even as a neophyte, who had written each of the pieces in the magazine, because each of these writers had such a distinctive voice.

In April 1934, Cantwell met Chambers' underground comrade, John Loomis Sherman, whom he knew as "Phillips."

Biographer Seyersted notes that in his 1952 memoir Witness, Chambers may have changed dates for his first meetings in Washington for the Ware Group to June and later in order to protect Cantwell.