Thelma Schoonmaker Powell was born in Algiers, Algeria, where her father worked for the Standard Oil Company. She grew up on the island of Aruba and after returning to the United States, attended Cornell University, where she studied political science and Russian, intending to become a diplomat. While doing graduate work at Columbia University, she answered a New York Times ad that offered on-the-job training as an assistant film editor. The exposure to the field sparked a desire to learn more about film editing, and her career was set.
During a six-week summer course at New York University’s film school she met Martin Scorsese and Michael Wadleigh. Within a few years she was editing Scorsese’s first feature, Who’s that Knocking at My Door (1967). She then edited a series of films and commercials before supervising the editing of Wadleigh’s 1970 film Woodstock, for which she was nominated for an Academy Award. In 1981 she won the Academy Award, the American Cinema Editors Eddie Award, and the BAFTA Award for her editing of Scorsese’s Raging Bull. Since then, she has worked on all of Scorsese’s feature films: The King of Comedy (1983), After Hours (1985), The Color of Money (1986), The Last Temptation of Christ (1988), the “Life Lessons” segment of New York Stories (1989), GoodFellas (1990) which earned her another BAFTA Award and another Oscar nomination, Cape Fear (1991), The Age of Innocence (1993), Casino (1995), Kundun (1997), Martin Scorsese’s documentary on the first 100 years of American film A Personal Journey with Martin Scorsese through American Movies (1995), Bringing Out the Dead (1999), Martin Scorsese’s documentary on the Italian Cinema Il Mio Viaggio in Italia (2001), Gangs of New York (2002) for which she earned another Oscar nomination and won the American Cinema Editors Eddie Award, The Aviator (2004), for which she won her second Academy Award and the American Cinema Editors Eddie, The Departed (2006) for which she won her third Academy Award and her fourth American Cinema Editors Eddie Award, Shutter Island (2010), Hugo (2011) for which she received an Oscar nomination, an American Cinema Editors Best Dramatic Film Editing nomination and a BAFTA nomination, and most recently Wolf of Wall Street (2013) for which she received an American Cinema Editors nomination and a BAFTA nomination.
In addition to editing, she works tirelessly to promote the films and writings of her late husband, the film director Michael Powell whose body of work includes such titles as The Red Shoes (1948), Black Narcissus (1947), The Life and Death of Colonel Blimp (1943), A Matter of Life and Death (1946) and Peeping Tom (1960).