She is described as a tall, very thin girl with long, frizzy brunette hair, somewhat similar to Sue's hairstyle. She was one of the girls who threw tampons at Carrie White in the locker room and ended up in detention with Miss Collins. After Carrie had gotten her period and sent to Mr Morton's office, she is seen walking with another girl to her class. For a brief second, she is seen walking down some stairs and then back up with her boyfriend while Freddy is talking to Ernest. At the prom, Ruth was with Helen Shyres and during Carrie's rampage, she tried to escape along with Helen, but both fell to the ground in the attempt. Ruth is last seen attending to Helen's body, but it appears to be too late.
- In the novel, she survives The Black Prom.
- This is the only adaptation where Ruth dies.
- She, along with Rhonda, Mary and Alice are the final Mortimer Snerds to be killed by Carrie White.