A native of Lake City, Florida, Allen attended Columbia High School, where he played linebacker and was an honor student as a senior.
Allen was named third-team all-state Class 6A, and was looking forward to a scholarship offer by University of Florida in Gainesville, just down the Interstate 75 from Lake City.
[2] After redshirting his first year in Tallahassee, Allen played all 12 games of the 1997 season as a back-up to Lamont Green and Deon Humphrey at strongside linebacker and on special teams.
In his sophomore year, Allen played in 11 games and finished sixth on the team with 57 tackles (31 solo), including six for a loss of yardage and three quarterback sacks.
[3] Allen was responsible for the only sack of Gators quarterback Doug Johnson, and added four tackles and two pass deflections, a performance for which he was named the Tomahawk Player of the Game by the coaching staff.
He also accounted for six quarterback hurries, ten pass-breakups (second-best on the team behind Tay Cody's twelve), two fumble recoveries and also had an interception in the 37–3 win over Virginia.