Also known as the "Melodic" or "Chromatic style", it was first developed and popularized independently by Bobby Thompson and Bill Keith in the early 1960s.
This contrasts with "3-Finger" or Scruggs style, which is centered on arpeggios, or chord tones played in rapid succession.
A distinct advantage of melodic style is the ease of playing fiddle tunes using the melody verbatim while maintaining a right hand technique in line with Scruggs-style.
The earliest recordings of the melodic style were made by Bobby Thompson in the late 1950s when he was in Jim and Jesse's band.
During the 1960s and '70s, the style steadily gained popularity among progressive bluegrass banjoists like Alan Munde, Tony Trischka, Courtney Johnson, Ben Eldridge and Gordon Stone.