The Altamont Pass is a mountain pass in Northern California, United States, located between Livermore in the Livermore Valley and Tracy in the San Joaquin Valley.

The pass carries Interstate 580 and a railroad route, originally owned by Western Pacific and today used for the Altamont Commuter Express with service to Pleasanton and San Jose.

The pass is known for its wind farm, one of the earliest in the United States. The wind farm is composed of over 4000 relatively small wind turbines of various types, making it the largest farm in the world in terms of number of turbines. They were installed after the 1970s energy crisis in response to favorable tax policies for investors. It has been said that their primary productivity is not electricity but rather tax write-offs. Considered largely obsolete these numerous small turbines are being gradually replaced with much larger and more cost effective units. The small turbines are dangerous to various raptors that hunt California ground squirrels in the area. The larger units turn slower and, being elevated higher, are less hazardous to the local wildlife. An advantage of this particular site is that under hot inland (California Central Valley) conditions a thermal low is developed that brings in cool coastal marine air through this pass, driving the turbines at a time of maximum need. Unfortunately this is not always reliable and with an inland high pressure condition the entire region can be both hot and windless. At this time additional power must be provided by natural gas powered gas turbine peaker plants.

See also: Altamont (disambiguation)