Mary Alice "Muffy" Crosswire is a student in Mr. Ratburn's third-grade class at Lakewood Elementary School. She is in Mr. Ratburn's class again for fourth grade. She is the richest girl in Elwood City and lives in an enormous mansion. Muffy entered Lakewood in second grade when she met Arthur and his friends and quickly became best friends with Francine. She is often labelled as snobbish and spoiled because of her wealth, attitude, and frequent selfishness,[9] but makes up for it in most cases.