Born Catherine Fink in St. Louis in 1909, Thompson was a piano prodigy who performed with the St. Louis Symphony at the age of 16. She graduated from Soldan High School and attended Washington University, where she was involved in many musical and theatrical groups. After college she left for Hollywood where she had a successful career as a vocalist and musical arranger. She worked as an arranger and songwriter for the “Ziegfeld Follies”, directed by Vincent Minnelli, and “The Harvey Girls”, starring Judy Garland. As a result of these connections, she was asked to be godmother to their daughter, Liza Minnelli. Thompson also sang with the Mills Brothers and performed with Andy Williams. She appeared in the movie “Funny Face” as Maggie Prescott.

In the 1950s Thompson decided to get out of the music business, and became a writer. Her “Eloise” series, about a precocious six-year old who lives in the luxurious Plaza Hotel in New York and travels in Paris, was a tremendous success. By 1963 more than a million copies of the series had been sold and the Plaza Hotel established an Eloise Room.