Harrington had scoring runs of 19, 8 and 4-yards in the first half as Lamar built a 42-7 lead at the break. Harrington added a 3-yard touchdown run late in the third quarter.
Caleb Berry threw a 59-yard touchdown pass to Mark Roberts, and hit Reggie Begelton for a 4-yard score. Berry was 27 of 32 for 330 yards, and his performance broke John Evans' school record for career completions, yards passing, and total offense set in 1989.
Carl Harris added 116 yards rushing and a touchdown for Lamar (5-3, 2-2 Southland Conference).