 While a student at El Monte High School, Neilson set CIF Southern Section records in 1972 for both the 50-yard and 100-yard freestyle events.She later attended University of California, Santa Barbara, where she was a member of the UCSB Gauchos swim team and a three-time All-American.In 1977, she won both the Association for Intercollegiate Athletics for Women (AIAW) 50-yard and 100-yard freestyle national championships.