Wild child/author Beverly Donofrio wanted Drew Barrymore to play her in the film adaptation of her memoir because "I'm not a very sympathetic character and Drew is inherently lovable." According to Drew, playing Bev in Riding in Cars with Boys gave her the insight she needed to reunite with her mom for Christmas for the first time in years. Drew's own "bad girl" past made her the ideal choice for the role of a teen girl who is pretty, smart and boy crazy.

In 1965, Bev Donofrio (Drew Barrymore) is a 15-year-old in a very strict, working class family in Connecticut. Her dream is to move to New York City and be a writer. Her teachers encourage her to go to college but, looking for love, she hooks up with Ray Hasek (Steve Zahn), a sweet but dim-witted 18-year-old high school dropout. Soon, Bev finds she is pregnant, a definite "no-no" in 1965. Her stern cop father (James Woods) is disappointed and embarrassed and her mom (Lorraine Bracco) is heartbroken.

Bev marries Ray, whom she really doesn't love, to save the family honor but having a son to care for and a husband who turns out to be a drug addict, smashes her plans to go to college. As the years pass, and Bev raises son Jason (played as an adult by Adam Garcia) alone, she relies on a close friendship with best girlfriend Fay (Brittany Murphy) who was also a teen mom. Years later, Jason is a young man and Bev is living in New York and about to have her first book published. Together, mom and son head for a brief reunion with Jason's dad that allows Jason to finally make a clean but friendly break with his mom and lead his own life.