The band evolved from Anything Muppet hippies that appeared in Muppet inserts, often in musical numbers, as early as Season 1. As with the nature of Anything Muppets, the physical puppets, clothes and facial features were often interchanged. One example is an insert with Grover on the word "exit," which sees the Green AM that would become Little Jerry rather than red. (First: Episode 0210)
The name "Little Jerry and the Monotones" first appeared on the second Sesame Street cast album. From there, the band members became personalities named after their primary performers; Little Jerry is named after Jerry Nelson, Big Jeffy after Jeff Moss, Chrissy after Christopher Cerf, and Rockin' Richard after Richard Hunt. The members are introduced individually by name in the song "Four." On occasion, the names and voices for the back-up singers have been swapped.
Although there were usually four members of the band, an extra member, an unnamed Purple Anything Muppet, appeared in the song "Body Rhythms." In their appearance in Episode 2452 (1988), the group consisted of Little Jerry, Big Jeffy, and another Fat Blue AM performed by Richard Hunt. At this point, the group's previous hippie attire were replaced with 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 Sesame Street Episode 3898 (2000), the group made a comeback appearance in a concert to perform "When You Move the Mouse." The group again is pared down to three members; with a Lavender member in an Elvis-like pompadour, named "Richie," playing the guitar.
Though the band members have been mostly consistent, their performers have occasionally varied, especially prior to Chris Cerf and Richard Hunt joining the show. The song "Surprise!" features an early iteration of the group; with a black-haired Lavender AM singing for Little Jerry, and Joe Raposo and Caroll Spinney providing backup vocals. Similarly, Thad Mumford supplied backup Monotone vocals for the song "With Every Beat of My Heart."
In one early appearance, the Monotones unenthusiastically assist Grover in demonstrating the word "Walk." (First: Episode 0221) Here, Jerry Nelson performs Big Jeffy, Caroll Spinney perform the Lavender and Pumpkin AMs, and Fran Brill performs Little Jerry.
- 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."