Mount Adams, known by some Native American tribes as Pahto or Klickitat, is a potentially active stratovolcano in the Cascade Range. Although Adams has not erupted in more than 1,000 years, it is not considered extinct. It is the second-highest mountain in the U.S. state of Washington, after Mount Rainier.

Adams, named for President John Adams, is a member of the Cascade Volcanic Arc, and is one of the arc's largest volcanoes, located in a remote wilderness approximately 34 miles (55 km) east of Mount St. Helens. The Mount Adams Wilderness consists of the upper and western part of the volcano's cone. The eastern side of the mountain is designated as part of the territory of the Yakama Nation.

Adams' asymmetrical and broad body rises 1.5 miles (2.4 km) above the Cascade crest. Its nearly flat summit was formed as a result of cone-building eruptions from separated vents. Air travelers flying the busy routes above the area sometimes confuse Mount Adams with nearby Mount Rainier, which has a similar flat-topped shape.

The Pacific Crest Trail traverses the western flank of the mountain.