The Angeles National Forest (ANF) of the U.S. Forest Service is located in the San Gabriel Mountains and Sierra Pelona Mountains, primarily within Los Angeles County in southern California. The ANF manages a majority of the San Gabriel Mountains National Monument.
The national forest was established in 1908, incorporating the first San Bernardino National Forest and parts of the former Santa Barbara and San Gabriel National Forests. Angeles National Forest headquarters are located in Arcadia, California.
The Angeles National Forest covers a total of , protecting large areas of the San Gabriel Mountains and Sierra Pelona Mountains. It is located just north of the densely inhabited metropolitan area of Greater Los Angeles.
While primarily within Los Angeles County, a small part extends eastward into southwestern San Bernardino County, in the Mount San Antonio ("Mount Baldy") area, and a tiny section also extends westward into northeastern Ventura County, in the Lake Piru area.
The San Gabriel Mountains National Monument, established in 2014 and managed by the U.S. Forest Service, is largely within the Angeles National Forest.
The John D. Dingell Jr. Conservation, Management, and Recreation Act of 2019 established the Saint Francis Dam Disaster National Memorial and Saint Francis Dam Disaster National Monument at and around the ruins of the St. Francis Dam in the Forest's San Francisquito Canyon.
The Angeles National Forest contains five nationally designated wilderness areas. Two of these also extend into neighboring San Bernardino National Forest:
Cucamonga Wilderness — mostly in San Bernardino National Forest
Magic Mountain Wilderness
Pleasant View Ridge Wilderness
San Gabriel Wilderness
Sheep Mountain Wilderness — partially in San Bernardino National Forest
The San Gabriel Forest Reserve was established on December 20, 1892, the San Bernardino Forest Reserve was established on February 25, 1893, and the Santa Barbara Forest Reserve was established on December 22, 1903.