"[1] Although she has written songs, she is notable chiefly for her interpretations of other artists' work.
While working in the fashion industry, she began to play in the coffeehouses of Greenwich Village and the church basements of the Upper West Side, and toured in Europe.
In 1980, her second album, Forgotten Dreams, consisting mainly of covers of songs by contemporary North American songwriters, was released on the Flying Fish label.
In 1982, Herdman left Philadelphia and moved to the small rural community of Pine Plains, New York, where she met her husband, Dick Hermans.
To date, Herdman has released 12 albums, including several in a trio with Anne Hills and Cindy Mangsen.