Bluegrass Music Bluegrass is a style of country and western music that developed during the 1940s, based on traditional ballads, fiddle tunes, and gospel hymnody of the southern Appalachian Mountains in the United States. It evolved from the backwooks, blue-collar music of the South, particularly Appalachia. Bluegrass features acoustic string band instruments such as the fiddle, banjo, and mandolin, accompanied by guitar and string bass. The lead instruments improvise virtuoistic solo choruses, somewhat like a country version of jazz. The singing style, often characterized as the "high lonesome sound", is pitched quite high and can include four-part harmony with a hig