Born in Orlando, Florida, Harrison is the twin brother of fellow Olympic medalist Calvin Harrison. A year before their first attempt to make the Olympic team, the twins were living in their Ford Mustang. While Calvin was the star in high school, setting the National High School Record in the 400 meters, it was Alvin who earned the first Olympic spot in 1996 at the 1996 Olympic Trials. While he made the finals in the individual 400 meters, he drew lane one and finished fourth behind Michael Johnson's gold medal performance. But Johnson injured himself setting the world record in the 200 meters. Without their Gold medalist and also without world record holder Butch Reynolds, the American team looked vulnerable in the 4 x 400 meters relay. The British team looked to take advantage by going out hard in the lead, however as the second leg of the team, Alvin over took Jamie Baulch on the home stretch to put USA into the lead, a lead they ultimately would not relinquish, giving Alvin a gold medal.