Harrington is a graduate of the University of Oregon, and was a three-year starter on the Oregon Ducks football team. In his senior season at Oregon, he threw for 2,415 yards and 23 touchdowns, and he finished his college career with a 25-3 record (including bowl wins against #12 Texas and #3 Colorado), 512 completions in 928 attempts (55.2%), 6,911 passing yards, 59 touchdowns, 23 interceptions, and 210 rushing yards and 18 scores on 145 carries. A business administration major with a 3.23 GPA (twice earning honors with a 3.34 GPA), Harrington's 7,121 yards of total offense rank third in University of Oregon history.