Cassill's wartime experiences culminated in his short story "The Conditions of Justice," published in 1947, and won him his first article in the Atlantic Monthly.
In 1949, he briefly served as an instructor at the Iowa Writer's Workshop before attending the Sorbonne in 1952 for a year as a Fulbright Fellow, studying comparative literature.
Assessing these early writings, The New York Times remarked that "Cassill shows that he can combine paperback storytelling at its strongest with subtle literary quality.
Notable students who took classes with Cassill at the Iowa Writer's Workshop during this time include Clark Blaise, Raymond Carver, and Joy Williams.
After retiring from Brown University, Cassill became the editor of The Norton Anthology of Short Fiction, retaining this position for nearly a quarter century, until his death.
[4] In 1973, Cassill created a controversy when his essay, “Up the Down Co-ed,” was published in Esquire magazine with the subtitle "Notes on the Eternal Problem of Fornication With Students."
Esquire had just published his piece “Up the Down Co-ed”, and the student newspaper at Brown had run the headline: Verlin Cassill: Another D.H. Lawrence or just a Dirty Old Man?
At the time of his death, he was survived by his wife, two sons (Orin E., of New York City, and Jesse B., of San Diego), and a daughter, Erica Cassill Wood of Saline, Michigan; a brother, H. Carroll, of Cleveland, Ohio; a sister, La Jean Holstein of Ellsworth, Maine; and seven grandchildren.