Mount Oso, or Cerro del Oso, is a prominent peak in the Diablo Range of western Stanislaus County, California. At 3,352 feet, it is the county’s third highest point and a familiar landmark visible from the valley floor, even appearing in the City of Modesto’s logo. About 10 miles west of Westley, it is closed to the public because it is surrounded by gated private property. Its Spanish name means bear, and Gabriel Moraga probably first noted it during Central Valley expeditions. With no known date for its first ascent, the mountain today supports several radio facilities and an unused forest fire lookout tower.