A golf club head with plate-like, heel and toe side internal stiffeners is disclosed herein. Each stiffener has a planar portion extending approximately parallel with a portion of the striking face, and is entirely disposed within an interior cavity of the golf club head. The heel side stiffener is connected to top, sole, and heel walls of the club head, with a toe-side edge unconnected to any other portion of the head, and the toe side stiffener is connected to the top, sole, and toe walls of the club head, with a heel-side edge unconnected to any other portion of the head. The toe and heel side edges may have large concavities that distribute mass away from the geometric face center and toward the heel and toe sides of the golf club head.