This is an examination of Leonard Bernstein’s impact as conductor and musical advocate. He was a champion of the works of Jean Sibelius and Gustav Mahler at a time when their work was unfashionable, bringing them to a much larger audience. The American composer he admired most was Aaron Copland, whose ’Connotations’ he led to open Lincoln Center for the Performing Arts. He was not in sympathy with most ‘12 tone’ music but did lead avant-garde works by the composers Lukas Foss, Elliott Carter, John Cage, and others. He conducted the world premiere of Olivier Messiaen’s ‘Turangalila Symphony’ in Boston in 1949 but never presented it again. He was an adept Straussian but only led the works composed before World War I. This was also his favourite period of Stravinsky’s work, although he added the three symphonies to his repertory in later years. On television, he led studies of rock and jazz. He conducted and recorded much of the standard repertory from the nineteenth century onwards, with only a few forays into Baroque and Classical-era music, with a particular emphasis on Haydn. There is some discussion of Bernstein’s podium manner and the conductors he influenced.