Nate Longshore was 17-of-31 for 176 yards with a pair of interceptions but had a rushing touchdown for the Golden Bears (6-1, 4-0 PAC 10), who have won six straight.
The normally high-powered Cal offense outgained the Cougars by only three yards, but the defense and special teams kept the Bears perfect in the conference.
Robert Jordan had six catches for 56 yards in the win, while DeSean Jackson added four receptions for 60 yards.
Darrell Hutsona rushed for 88 yards for Washington State (4-3, 2-2). Alex Brink was 19-of-35 for 227 yards with an interception.