The standard ascent route is the West Side Route, accessed from Shepherd's Pass.
From the pass, one travels across the Williamson Bowl, which lies between Mount Williamson and Mount Tyndall, part of the Sierra Crest.
The bowl is home to five high alpine lakes.
From the bowl, the route climbs gullies up the west face to the relatively broad summit plateau; this portion involves scrambling up to class 3.
Technically easier, but with a more difficult approach which can involve route finding and bushwhacking, is the Southeast Slopes Route, rising from George Creek.
Other routes exist on the mountain, including a significant technical route on the North Rib (Grade IV, 5.7).

Climbing Mount Williamson is made more difficult by the lengthy and strenuous approach.
Elevation gain from the trailhead is over 8,000 feet (2,400 m), and the trail to Shepherd's Pass alone is 11 miles (18 km).

Mount Williamson is in the California Bighorn Sheep Zoological Area and these rare animals can often be seen on the lower slopes during the winter when heavy snows drive the sheep down from their summer grazing areas.
From 1981 until 2010 the California Bighorn Sheep Zoological Area was closed to access for much of the year, but late in 2010, the Inyo National Forest Service declined to renew the closure, opening the area to access year-round.
The standard ascent route is the West Side Route, accessed from Shepherd's Pass. From the pass, one travels across the Williamson Bowl, which lies between Mount Williamson and Mount Tyndall, part of the Sierra Crest. The bowl is home to five high alpine lakes. From the bowl, the route climbs gullies up the west face to the relatively broad summit plateau; this portion involves scrambling up to class 3. Technically easier, but with a more difficult approach which can involve route finding and bushwhacking, is the Southeast Slopes Route, rising from George Creek. Other routes exist on the mountain, including a significant technical route on the North Rib (Grade IV, 5.7).
Climbing Mount Williamson is made more difficult by the lengthy and strenuous approach. Elevation gain from the trailhead is over 8,000 feet (2,400 m), and the trail to Shepherd's Pass alone is 11 miles (18 km).
Mount Williamson is in the California Bighorn Sheep Zoological Area and these rare animals can often be seen on the lower slopes during the winter when heavy snows drive the sheep down from their summer grazing areas. From 1981 until 2010 the California Bighorn Sheep Zoological Area was closed to access for much of the year, but late in 2010, the Inyo National Forest Service declined to renew the closure, opening the area to access year-round.
Mount Williamson