The Hoosiers (3-2, 1-0 Big Ten) capped their five-game home stand by ending a 16-game losing streak to the Nittany Lions (3-2, 0-1).
It looked like Penn State might keep the streak alive after taking its first lead of the game on a 26-yard TD pass from Christian Hackenberg to Allen Robinson early in the third quarter.
But Indiana answered with a scoring flurry.
Tevin Coleman scored on a 44-yard run and Roberson scored on a 2-point conversion run. Roberson then added a 2-yard TD run early in the fourth and after Penn State failed on fourth-and-2 from its own 33, Kofi Hughes made a catch for a 36-yard TD and a 35-17 lead. Roberson followed with a 9-yard TD run to seal it.
The Hoosiers finally figured out how to effectively use their top two quarterbacks -- Sudfeld and Roberson -- and wound up with their first win in a conference opener since 2000.
Sudfeld finished 23 of 38 for 321 yards passing with one interception and one touchdown pass in each half. Roberson wound up in the end zone on each of his first three touches -- all quarterback keepers inside Penn State 10-yard line.
But the Hoosiers did more than light up the scoreboard.
Coleman ran 20 times for 92 yards and a score, Cody Latimer caught nine passes for 140 yards and went over the 100-yard mark for the third-straight game, and the defense that had ranked among the worst in the nation against the run limited Penn State to just 70 yards on the ground.
It was a rough start for the Nittany Lions, who failed to convert either of their first two drives into points.
The first ended at the Indiana 26 on a failed fourth-down gamble. After forcing a three-and-out, the Nittany Lions drove to the Indiana 14, but a bad snap in soggy conditions bounced past holder Ryan Keiser and kicker Sam Ficken fell on it for a 31-yard loss. Those missed chances proved costly.
Indiana broke a 7-7 tie with two short field goals at the end of the first half to make it 13-7.
And then, after Robinson gave Penn State its only lead of the day, the Hoosiers responded with their flurry.
Hackenberg was 30 of 55 for 340 yards passing with three TDs and one interception. Robinson finished with 12 receptions for 173 yards and two TD catches, moving from 12th to seventh (118) on the Nittany Lions career receptions list and into a tie with O.J. McDuffie for fifth on the school's all-time list for TD receptions (16).