From Dodsworth (1936) to Porgy and Bess (1959), Mandell worked for Samuel Goldwyn Productions.
He had notable collaborations with directors William Wyler (1933–1946) and Billy Wilder (1957–1966).
Mandell won the Academy Award for Best Film Editing for The Pride of the Yankees (1942; directed by Sam Wood), The Best Years of Our Lives (1946; directed by William Wyler), and The Apartment (1960; directed by Billy Wilder).
[4] Mandell was nominated for the Academy Award for two additional films, The Little Foxes (1941; directed by William Wyler) and Witness for the Prosecution (1957; directed by Billy Wilder).
Additional credits include Holiday (1930), Counsellor at Law (1933), Dodsworth (1936), Wuthering Heights (1939), Meet John Doe (1941), The North Star (1943), Enchantment (1948), Roseanna McCoy (1949), Guys and Dolls (1955), and Kiss Me, Stupid (1964).