Old Baldy is a 9,156-foot (2,791-metre) double summit mountain located in Teton County of the U.S. state of Montana.

It is situated 11 miles east of the Continental Divide, in the Bob Marshall Wilderness, on land managed by Lewis and Clark National Forest.

Precipitation runoff from the east side of the mountain drains into headwaters of South Fork Teton River, and the west side drains into tributaries of the North Fork Sun River.

Topographic relief is significant as the east aspect rises 3,350 feet (1,020 meters) above South Fork Teton River in two miles.

[4] The Lewis Overthrust extends over 280 miles (450 km) from Mount Kidd in Alberta, south to Steamboat Mountain which is located 40 miles south of Old Baldy, which places Old Baldy within the southern extent of the Lewis Overthrust.