The son of the noted Chicago humorist, baseball writer and playwright attended Andover and Princeton, where he joined the Socialist Club. In his sophomore year he enrolled at the Anglo-American Institute of the University of Moscow, which was established to familiarize young Britons and Americans with the wonders of the Soviet system. Lardner returned to New York and, in 1935, briefly worked at the Daily Mirror before signing on as publicity director with David O. Selznick’s start-up movie company. Lardner got his big break when Selznick partnered him with Budd Schulberg, a reader in the story department who would later cooperate with HUAC. The two rookies punched up a few scenes in A Star is Born, a 1937 feature starring Fredric March and Janet Gaynor that became a critical and box-office success.

By 1937 Lardner had been recruited by the Communist Party in Hollywood and was attending a Marxist meetings four nights a week. In time he became a member of such groups as the Hollywood Anti-Nazi League and the Hollywood Writers Mobilization Against the War. He also served on the board of the Screen Writers Guild.

In 1942, he co-wrote Woman of the Year with Michael Kanin. The comedy marked the first onscreen collaboration between Katharine Hepburn and Spencer Tracy and won Lardner and Kanin an Oscar for original screenplay. In 1947 he became one of the highest-paid writers in Hollywood when he signed a contract with 20th Century Fox at $2,000 a week. A few months later he stood by his fellow members of the Hollywood Ten in refusing to testify before HUAC. Lardner replied to the standard question — “Are you now or have you ever been …” — by noting, “I could answer the question exactly the way you want, but if I did, I would hate myself in the morning.” The aggressive committee chairman, J. Parnell Thomas, a Republican from New Jersey, angrily dismissed Lardner from the stand.

By the time Lardner began to serve his sentence for contempt of Congress in 1950, former Rep. Thomas was in the same federal penitentiary in Danbury, Conn., after his conviction of defrauding the government by putting fictitious workers on his payroll. Behind bars, the screenwriter and the HUAC chairman “became reacquainted,” as Lardner later wrote.

After his release, Lardner wrote a novel, The Ecstasy of Owen Muir (1954), and then moved to England where he wrote under several pseudonyms for television series such as The Adventures of Robin Hood. His blacklisting ended when producer Martin Ransohoff and director Norman Jewison gave him screen credit for writing The Cincinnati Kid (1965). Lardner's later work included M*A*S*H (1970), for which he won the Academy Award for an adapted screenplay.

Although Lardner allowed his party membership to lapse in the 1950s, he said in an interview with The New York Times that “I've never regretted my association with communism. I still think that some form of socialism is a more rational way to organize a society, but I recognize it hasn't worked anywhere yet.” He died in Manhattan in 2000 at age 85, the last surviving member of the Hollywood Ten.