Born on November 18, 1985, Felix grew up in Santa Clarita, California. Her father, Paul, is a Baptist minister who had once been an excellent sprinter as a teen, and from her schoolteacher mother, Marlean, she inherited her long legs. Felix followed her older brother, Wes, into the sport, though she did not try out for a track team until her ninth-grade year at Los Angeles Baptist High School in North Hills.
That March of 2000 date proved an apocryphal one: she was the first to make a run when the coach, Jonathan Patton, lined up the possible sprinting stars during tryout week. She ran it so fast that he thought he had mis-measured the distance, but then the other runners who came after her clocked in normal times. She ran it again at his request, and with the same result. In 2003, Felix turned in an impressive performance when she competed in the Banamex Grand Prix in Mexico City’s Olympic Stadium. She broke her own record in the 200-meter, clocking a time of 22.11 seconds, which was a new world record in the under-20 category. At the Banamex, Felix also matched Marion Jones’s best time in the 200-meter from the previous year, and beat Inger Miller as well, the 1999 world champion. Felix emerged as the new American female runner to watch, just as Jones was taking some time off to have a baby. Some weeks after her dazzling Mexico City run, Felix learned that her 22.11 was a U.S. national record time, but would not be posted as the new world junior record in the 200-meter because she didn’t take a drug test within an hour after finishing. She learned this only in July of 2003, when she traveled to Paris for an international meet. “It does bother me a little bit, but not too much,” she said in an interview with Daily News journalist Matthew Kredell. “I still ran the same time. It’s unfortunate that I’ve been drug-tested so many times and, for whatever reason, it didn’t happen at this meet.” After graduating from Los Angeles Baptist High School in 2003, Felix decided to turn professional. She began attending the University of Southern California, but did not run for its team. Instead she signed with Adidas, a deal that made her ineligible to compete in college events.
She continued to train and work with coach Pat Connolly, a former Olympic runner who coached Evelyn Ashford to an Olympic gold medal in 1984. In June of 2004, while training for the Olympics, Felix found herself short of breath, and was diagnosed with exercise-induced asthma. Even so, at the 2004 Olympic Games Allyson Felix won a silver medal in the 200-meter dash.