Chalich completed 29 of 49 passes with Chase Naccarato catching 13 for 84 yards, both career highs. Chalich started 4 of 10 for 14 yards before connecting on nine straight.
Chalich, who also led the team in rushing with 64 yards on 17 attempts, had touchdown passes of 20 yards to Ben Roberts and 42 yards to Jamaal Jones in the first half to give the Grizzlies (3-2, 2-0 Big Sky Conference) a 14-13 lead. He hit Ellis Henderson with a 4-yard TD in the third quarter.
The Aggies (0-5, 0-2) had four turnovers with Caleb Kidder recovering a fumble and intercepting a pass for Montana.
Montana iced the game with a 16-play, 85-yard drive in the fourth quarter capped by Jeremy Calhoun's 5-yard run.