He played college football at Northwestern University playing in 49 games with 36 starts and starting 36 of his last 37 games. A versatile player, Cofield started at right defensive tackle, left defensive end and left defensive tackle during his career. He finished with 197 tackles (88 solo), 6.5 sacks, and 15.5 stops for losses and registered 18 quarterback pressures with 8 pass deflections and a 16-yard interception return. He also recovered 3 fumbles and forced 4 others. He posted 5.5 of his 6.5 sacks and 11.5 of his 15.5 stops behind the line of scrimmage in his last 2 years. He played in every game as a true freshman in 2002 and registered 36 tackles (14 solo) with 2 stops for losses while causing and recovering a fumble in 12 contests. He earned a starting job at left defensive end as a sophomore and had 46 tackles (19 solo) in 13 contests. He added 1 sack, 2 stops for losses, 6 quarterback pressures, a forced fumble and a fumble recovery. He played right defensive tackle in 2004, when he started 11 games, collected 52 tackles with 3.5 sacks and 5 stops behind the line of scrimmage. Cofield added 5 pressures and batted away 3 passes. He earned Second-team All-Big Ten honors as a senior in 2005, when he lined up at left defensive tackle and recorded a career-high 63 tackles (24 solo) and had 2 sacks with 6.5 stops for losses and 7 pressures. He forced 2 fumbles, recovered another, deflected 5 passes and returned an interception 16 yards.