- "And here’s where you folks will be staying: the Caterpillar Room."
- —Lotso, assigning Andy's toys to the Caterpillar Room
The toddler children homeroom of Sunnyside opposite to the Butterfly Room, located across the corner of the only corridor, where the older children use the toys at their leisure appropriately. Woody leaves instantly after still believing that Andy still wants them and, unable to persuade the group, leaves them in the care of the children of the room. When the bell rings, the remainder of Andy's toys start to prepare to be played with, but Buzz notices some toys trying to hide underneath a desk and a bucket, indicating that the Caterpillar Room was not as toy-friendly as Lotso previously implied. Rex reaches the door and is knocked to the side, and his tail is removed roughly; Buzz is licked on his helmet and used in a hammering fashion; Jessie's ponytail is used as a paint brush; Mr. and Mrs. Potato Head are dismembered part to part, their pieces are chewed on, and they are drawn upon; the Aliens are bounced on and become tangled in Slinky's spring; Bullseye is thrown (in similarity to Rex, but left the most unharmed); and Hamm is filled with toys (one of them being Mrs. Potato Head's arm) and has noodles and glitter stuck to his back by glue.
Buzz eventually catches onto the true purpose of them in the Caterpillar Room and is soon abducted upon breaking out and following Ken, Twitch, and Chunk inside the Vending Machine. Lotso offers him a chance at redemption, but neglects in family which triggers Lotso's bad memory streak of Daisy's replacement, and then switches him to Demo Mode. Buzz then locks up the toys and a reluctant to remain with Ken and Barbie. From there, they thwart Lotso, and the Caterpillar Room still serves to most of the hiding toys, save for Chatter Telephone who has been there for years.
After Sunnyside is revolutionized into a true toy paradise by its new leaders Ken and Barbie, the Caterpillar Room is transformed into a sporting event, where toys, including those from the Butterfly Room, take turns experiencing the rough playtime with the toddlers.