Breeden qualified to compete in the 100-meter and 200-meter butterfly events at the 2008 Summer Olympics by placing second and first, respectively, in those events at the U.S. Olympic Trials. At the 2008 Olympics in Beijing, China, she advanced to the semifinals of the women's 100-meter butterfly, and finished seventh in the final of the women's 200-meter butterfly. She earned a silver medal by swimming for the second-place U.S. team in the preliminary heats of the women's 4×100-meter medley relay.