Justin Arias threw for 318 yards and a career-high tying four touchdowns for Idaho State (1-2).
Idaho State scored touchdowns on six out of seven possessions and opened up a 39-13 lead with 4:38 left in the third quarter.
On Idaho State's next drive, a 27-yard field goal attempt was blocked and returned 80-yards for a touchdown by Jordan Jones, pulling Chadron State within 19 and sparking a rally.
Chadron State scored on a 39-yard touchdown run by Michael Madkins and - following a fumble that was forced and recovered by Ryan Wood - a 25-yard touchdown pass from John McLain to Danny O'Boyle to make it 39-34 with 1:22 remaining.
An onside kick by Randy Wentz went out of bounds before Idaho State bled the clock.