Eagle Cap Wilderness is a wilderness area located in the Wallowa Mountains of northeastern Oregon (United States), within the Wallowa–Whitman National Forest. The wilderness was established in 1940. In 1964, it was included in the National Wilderness Preservation System. A boundary revision in 1972 added 73,000 acres (30,000 ha) and the Wilderness Act of 1984 added 66,100 acres (26,700 ha) resulting in a current total of 361,446 acres (146,272 ha; 565 sq mi), making Eagle Cap by far Oregon's largest wilderness area.
Eagle Cap Wilderness is named after a peak in the Wallowa Mountains, which were once called the Eagle Mountains. At 9,572 feet (2,918 m) Eagle Cap was incorrectly thought to be the highest peak in the range, hence the name.