Despite forcing the Raiders into 28 mistakes, Penn (8-8) trailed by double digits for most of the game, including being behind 44-27 at the break.
The Lady Statesmen cut the deficit to 15 points at 70-55 with 8:34 left, but could come no closer.
Northwestern (10-2) outshot Penn 57.7%-32.4%, but the hosts held a 22-20 edge in free throws and a 15-14 advantage in steals.
Christa Subbert (Jr., Stanton, Stanton HS) topped the Lady Statesmen with 12 points, while three others also reached double figures.
Nancy Chicas (Sr., San Francisco, Calif., San Mateo CC) managed 11 points and
Samantha Darley (Jr., Gilbert, Ariz., Mesa CC) and
Raven House (So., New Orleans, La., Cabrini HS) added ten points apiece.
The trio of
Rachel Butler (Jr., Anaheim, Calif., Cerritos CC),
Carleigh Hobson (Jr., Lancaster, Calif., Antelope Valley CC), and
Ashton Perez (Jr., Wildomar, Calif., Riverside CC) all contributed eight points in the loss. Butler also led all players with eight rebounds and five steals (tie). Chicas dished out a team-high four assists.
Next: Penn is off until after the Christmas break. The Lady Statesmen return to action on Saturday, January 2 when they travel to Dubuque to face Clarke in Midwest Collegiate Conference action at 1 p.m.