He began playing guitar in high school, partially inspired by the album Jimmy Reed at Carnegie Hall.

He befriended and recorded with many electric blues musicians in New York, including Jimi Hendrix, Eric Clapton, Levon Helm's New Hawks (later known as the Band), Mike Bloomfield, Dr. John, and Duane Allman.

Hammond usually plays acoustically, choosing National Reso-Phonic Guitars, and sings in a barrelhouse style.

Nonetheless, he enjoys a strong fan base and has earned respect from John Lee Hooker, Roosevelt Sykes, Duane Allman, Rory Gallagher, Willy Deville, Robbie Robertson, Mike Bloomfield and Charlie Musselwhite, all of whom have contributed their musical talents to his records.

In addition, he is the only person who ever had both Eric Clapton and Jimi Hendrix in his band at the same time, if only for five days in the 1960s, when Hammond played The Gaslight Cafe in New York City.

He recorded with several members of The Band in 1965 and recommended them to Bob Dylan, with whom they undertook a famed and tumultuous world tour.

In 2001, he released Wicked Grin, an album consisting entirely of Waits compositions, with one exception, the traditional spiritual, "I Know I've Been Changed".