During the 2008 Summer Olympic Games in Beijing, China, Steffen won the 100-meter freestyle, catching world record-holder Libby Trickett of Australia at the last stroke. Steffen touched in 53.12 seconds, bettering her own Olympic record of 53.38 set on the leadoff leg of the 4×100 m freestyle relay. Steffen then edged out Dara Torres to win the 50-meter freestyle gold with a time of 24.06 seconds, winning by 0.01 seconds.