She first learned to swim at the local Sherwood Golf and Swim Club, where she began to excel in the breaststroke. She qualified for the Women"s Senior National Championships in the 200-meter breaststroke at age 12, the youngest swimmer to participate. As a 14-year-old, Schoenfield was the second fastest women"s 200 meter breaststroke swimmer in the country, and just missed making the United States. team for the 1968 Summer Olympics.
After semi-retiring for the next three years, she was a varsity cheerleader for Loara High School in Anaheim, California.
After graduation, Schoenfield, along with her swim coach Ray Woods, began a one-year regimen of serious training in an effort to make the United States. team for the 1972 Summer Olympics. At the 1972 United States. Olympic Trials, she qualified first in the 200-meter breaststroke, with a personal best time of 2:43.7.
At the 1972 Olympics in Munich, she was not expected to contend for a medal as she had just the fourth fastest time and ranking for 1972. She placed fourth in the qualifying heats, and was in lane 6 for the Munich final.
With her swim idol, Galina Prozumenschikova of the Soviet Union, swimming in lane 3, she out-touched Prozumenschikova with a time of 2:42.03, another personal best.
Australian Beverley Whitfield, on the outside Number. 7 lane, beat Schoenfield for the gold medal at 2:41.7. After the 1972 Olympics, Schoenfield attended University of California, Los Angeles (University of California, Los Angeles), where she helped start the University of California, Los Angeles Bruins women"s swimming team under the auspices of the Association for Intercollegiate Athletics for Women (AIAW).
In 1973, she qualified for the World University Games in Moscow, Russia.
Afterward, retiring from swimming, she was selected to the 1975-1976 University of California, Los Angeles Spirit Squad as a songgirl/dance team member, where she performed at the 1976 Rose Bowl and the National Collegiate Athletic Association men"s basketball Final Four. The family now resides in Dana Point, California.
She is a swim coach and dean at Santa Margarita Catholic High School in Rancho Santa Margarita, California.