Leacock began his film career working on Robert Flaherty's "Louisiana Story" (1948) and collaborated with several other noted documentarians before forming his own production company with Robert Drew in 1958. While at Drew Associates, he turned out a number of TV documentaries, including the innovative "Living Camera" series, which established him as a pioneering figure of American "direct cinema" (a movement similar to, and concurrent with, France's "cinema verite"). Leacock has also worked with Albert Maysles and D.A. Pennebaker (with whom he formed a production company in 1963), and played his first dramatic part as one of the "johns" in Lizzie Borden's "Working Girls" (1986). His late brother Philip Leacock was a director and producer of both film and television. His son Robert and daughter Victoria are also filmmakers.