Tanglewood Music Festival, formerly the Berkshire Festival (until 1984), summer music festival held since 1937 at "Tanglewood," a former estate in the adjoining towns of Stockbridge and Lenox, Mass. The Berkshire Festival was begun in 1934 at a farm in Stockbridge. Henry Hadley conducted an orchestra composed largely of members of the New York Philharmonic for two summers. In 1936, Serge Koussevitzky and the Boston Symphony Orchestra took over the festival, which became its summer home. Charles Münch began as musical director of the festival in 1951 and was followed by William Steinberg, who conducted there through the summer of 1969. From 1974 to 2002, Seiji Ozawa was the artistic director, and James Levine has directed the festival since 2004. In 1940 a summer school, the Berkshire (now Tanglewood) Music Center, was begun in combination with the festival. Today it is one of the world's preeminent training grounds for composers, conductors, instrumentalists, and vocalists.

The Koussevitzky Music Shed at Tanglewood, designed by Eliel Saarinen, opened in 1938. Its acoustics were enhanced by the addition of an orchestra canopy in 1959. The Shed seats more than 5,000 people and accommodates about 12,000 additional listeners on its vast lawns. In 1986 the festival grounds were expanded from the original 180 acres (73 hectares) to 300 acres (121 hectares). In 1994 an additional facility, the 1,180-seat Seiji Ozawa Hall, was opened. Intended for chamber concerts, rehearsals, recitals, and recording sessions, it also contains a library, performers' pavilion, and other facilities, and accommodates some 2,000 concertgoers on its lawns.

See studies by J. R. Holland (1973), H. Kupferberg (1976), and A. L. Pincus (1989 and 1998).