Is there a movie based of the book rules by Cynthia Lord?

Yes, there is a movie based on the book "Rules" by Cynthia Lord. The movie, also titled "Rules", was released in 2003 and stars Alexa Vega, Katie Holmes, and James Caan. It follows the story of twelve-year-old Catherine, who struggles with Asperger's Syndrome and her relationship with her family and friends as she navigates middle school.