Penn State (10-19, 2-15 Big Ten), last in the 12-team conference, scored the game's first 12 points, withstood a Northwestern surge, then pulled away in the second half. The Nittany Lions' only other conference win was at home against No. 7 Michigan on Feb. 27.
Northwestern (13-17, 4-13) has lost seven in a row.
Northwestern's Alex Marcotullio, who scored a career-high 22 points, put the Wildcats ahead 54-53 with a 3-pointer with 6:13 to play. But Penn State scored the next six points, beginning with Sasa Borovnjak's short jumper, and scored 13 of the game's last 18 points. Borovnjak had 15 points and 10 rebounds.
Reggie Hearn, who scored 11 points before fouling out with 3:07 to play, was the only other Northwestern player in double figures.