Kees van Baaren (22 October 1906 in Enschede 2 September 1970 in Oegstgeest) was a Dutch composer and teacher.
Van Baaren's early studies (1924-29) were in Berlin with Rudolph Breithaupt (piano) and Friedrich Koch (composition) at the Stern conservatory. After returning to the Netherlands in 1929, he studied with Willem Pijper. He adopted Pijper's "germ cell technique" in his compositions from about 1934 onward. While composing some works in an accessible, tonal style, in other pieces he developed toward a serial technique, which emerged fully with the Septet for five winds, violin, and double bass (1952). He was the first important Dutch composer to use twelve-tone technique.
In 1948 Van Baaren became director of the Conservatoire of the Amsterdam Muzieklyceum Society (later merged into the Conservatoire of Amsterdam). In 1953 he was appointed director of the Utrecht Conservatoire. In 1958 he became director of the Royal Conservatory in The Hague. His students included many of the leading composers and performers of the next generation, including Louis Andriessen, Reinbert de Leeuw, Misha Mengelberg, Peter Schat, and Jan van Vlijmen.