[3][4] In 1958 to 1959, Prestopino played on Sundays in Washington Square Park in New York City's Greenwich Village with the Greenbriar Boys.

[5] He left the Greenbriar Boys before they became nationally known[6] to serve as an accompanist for the Chad Mitchell Trio,[7] and he also played behind Peter, Paul & Mary for at approximately fifteen years.

He contributed to albums by bands and singers such as Aerosmith, Rick Derringer, Alice Cooper, Pete Seeger, John Denver, Tom Paxton, and Judy Collins[11] among others.

[11] In the second half of his life, Prestopino played frequently in small musical venues within driving range of his home, including the New Jersey Folk Festival and Howell Living History Farm,[12] where he typically appeared with Jugtown Mountain String Band.

[15] He performed annually for many years at the New England Folk Festival in Boston with his English Country Dance band (called Hold the Mustard).