In music theory and music criticism, the term eclecticism refers to use of diverse music genres. A musician might be described as eclectic if different parts of their output can be ascribed to different genres such as folk, rock, electronic, classical, or jazz.

Eclectic musicians may also use historical references in their work. A song can reference historical forms and methods through its composition, arrangement or production.

The Beatles' output is characterised by the group's stylistic eclecticism.

The 1968 song Honey Pie is a useful example of these eclectic methods of music writing.

In the song's introduction, for example, Paul McCartney's vocals are EQ-ed to resemble a 1930s-style radio announcement, with additional vinyl crackles ('Now she's hit the big time!').

The song is also historicised by its arrangement. The accompanying jazz wind ensemble resembles the ragtime, vaudeville and music hall styles popular in early 20th century Britain.

The term can be used to describe the music of composers who combine multiple styles of composition; an example would be a composer using a whole tone scale variant of a folk song in a pentatonic scale over a chromatic counterpoint, or a tertian arpeggiating melody over quartal or secundal harmonies.

Eclecticism can also occur through quotations, whether of a style,^{[n 1]} direct quotations of folk songs/variations of them—for example, in Mahler's Symphony No. 1—or direct quotations of other composers, for example in Berio's Sinfonia.^[1]

• Polystylism
• Progressive music

• Kennedy, Michael, and Joyce Bourne (eds.). 2006. "Eclecticism", in The Oxford Dictionary of Music. Oxford and New York: Oxford University Press.
• Cope, David 1997. "Decategorization." Techniques of the Contemporary Composer,^{[page needed]}. New York: Schirmer Books; London: Prentice Hall International. ISBN 9780028647371.