Just was born in Michigan City, Indiana, attended Lake Forest Academy, and subsequently graduated from Cranbrook School in 1953. He briefly attended Trinity College in Hartford, Connecticut. He started his career as a print journalist for the Waukegan News-Sun. He was also a correspondent for Newsweek and The Washington Post from 1959 to 1969, after which he left journalism to write fiction.

His influences include Henry James and Ernest Hemingway. His novel An Unfinished Season was a finalist for the Pulitzer Prize for Fiction in 2005. His novel Echo House was a finalist for the National Book Award in 1997. He has twice been a finalist for the O. Henry Award: in 1985 for his short story About Boston, and again in 1986 for his short story The Costa Brava, 1959. His fiction is often concerned with the influence of national politics on Americans' personal lives. Much of it is set in Washington D.C. and foreign countries. Another common theme is the alienation felt by Midwesterners in the East.

According to Washington Post book critic Jonathan Yardley, Just's three finest novels are A Family Trust, An Unfinished Season and Exiles in the Garden.

Novels

• A Soldier of the Revolution (1970)
• Stringer (1974)
• Nicholson at Large (1975)
• A Family Trust (1978)
• In the City of Fear (1982)
• The American Blues (1984)
• The American Ambassador (1987)
• Jack Gance (1989)
• The Translator (1991)
• Ambition & Love (1994)
• Echo House (1997)
• A Dangerous Friend (1999)
• The Weather in Berlin (2002)
• An Unfinished Season (2004)
• Forgetfulness (2006)
• Exiles In The Garden (2009)

Story collections

• The Congressman Who Loved Flaubert (1973)
• Honor, Power, Riches, Fame, and the Love of Women (1979)
• Twenty-one: Selected Stories (1990)
• Lowell Limpett and Two Stories (2001)

Nonfiction

• To What End (1968)
• Military Men (1970)

Plays

• Lowell Limpett (2001)

Anthologized in

• Reporting Vietnam: American Journalism 1959-1969 (Part One) (1998)