allen played high school football at hialeah-miami lakes high school in hialeah, florida. a preseason fractured fibula ended his 2006 senior season before it ever began. however, he rushed for 1,095 yards and 12 touchdowns as junior in 2005, despite missing three games to injury. he was selected for 2007 u.s. army all-american bowl in san antonio but did not participate because of his injury. considered a four-star recruit by "rivals.com", allen was listed as the no. 2 all-purpose back in the nation. he chose notre dame over offers from tennessee, duke and florida.