All members of the band are named after the people who served as their original (and primary) voices: Little Jerry is named after Jerry Nelson, Jeff Moss supplied the voice for Big Jeffy, Rockin' Richard's by Richard Hunt, and Christopher Cerf was Chrissy. The individual members introduced themselves by name in the song "Four," while the group name first appeared on a 1971 record. On occasions, the names and voices for the back-ups, especially the latter two, were swapped.
Although there were usually four members of the band, an extra member, a nameless Purple Anything Muppet, appeared in the song "Body Rhythms." In a late 1980's appearance, the group consisted of Little Jerry, Big Jeffy, and another Fat Blue Anything Muppet performed by Richard Hunt. At this point, the group's previous hippie attire were replaced by more contemporary, yet still flashy clothes. The trio can also be spotted in a framed photo in Jackman Wolf's studio in the 1990 video Rock & Roll. In addition, the entire original group (complete with hippie garb) appear near the end of the video reprising their hit song "Telephone Rock."
In a 2000 episode of Sesame Street, the group made a comeback appearance in a concert to perform "When You Move the Mouse." The Pumpkin Monotone was absent in this performance. The Lavender member of the band appeared with an Elvis-like pompadour and went as "Richie" for this episode.
Members of Little Jerry and the Monotones appeared in two early 70s sketches with Grover, as background characters. In one sketch, Grover demonstrates the word "Exit", with the band exiting and entering the door where the exit sign is. (EKA: Episode 0261) In another sketch, Grover demonstrates the word "Walk" with members of the band, which here includes the lead singer from "Surprise!" (performed here by Caroll Spinney), holding up the letters representing the word. All of the members are performed by different puppeteers in this sketch.
- Before their main performers became consistent (mostly before Cerf and Hunt joined the show), the band members were voiced by other performers in their earlier appearances, including Joe Raposo, Caroll Spinney, and Fran Brill. In the song "With Every Beat Of My Heart", Thad Mumford provides Rockin' Richard's voice. In the group's 1980s episode appearance, Kevin Clash performs Big Jeffy.
- In addition to usually providing two of the back-up vocals, Jeff Moss and Christopher Cerf wrote most of the group's songs.
- The Monotones (without Little Jerry) also sang back-up for Don Music, in the song "Mary Had a Bicycle."