Each instrument plays a key role: the mandolin is a defining feature, the banjo is crucial for its signature sound, and the upright bass provides the deep foundation.
[2] In some traditional bluegrass bands, the guitar rarely takes the lead, instead acting as a rhythm instrument, one notable exception being gospel-based songs.
Bluegrass music is often defined by its distinctive features, such as the three-finger banjo picking, smooth, bluesy fiddling, and high-pitched, tense vocal harmonies.
Originally set apart from mainstream country music due to its emphasis on nostalgia and rural myths, bluegrass has since incorporated influences from genres like country-western, western swing, folk-rock, and jazz.
[3] Bill Monroe's mandolin playing style and Kenny Baker's fiddling set the standard for traditional bluegrass musicians on those instruments.
However, stylistic divergences in traditional bluegrass generally center on which first generation bands from which contemporary musicians have drawn inspiration.