Location: Los Angeles County, California

Named in July 1875 by three members of the Wheeler Survey (Dr. F. Kampf, W.A. Coles and Frank Holland) who were "disappointed" when they made the first recorded ascent of this peak. They had intended to use it as a triangulation point (because it appears to be the high point when climbed from the north), but they discovered it is over 150 feet lower than nearby San Gabriel Peak. In 1886 Perry Switzer built a trail to the summit from his nearby camp. That year Mrs. J.D. Hooker, by climbing this summit, became the first woman to make a recorded ascent in the San Gabriels.

In 1955 the summit was flattened for an Army Nike missile station whose buildings still remain although use was abandoned in 1965. This effluvia greatly degrades the peak experience for visitors and for many the peak sadly continues to live down to its name.

Robinson differs with Sam Fink's tentative assertion that Mount Disappointment might have been named by an early survey team, and reasserts that this use-name came Into currency much later (ca. 1925-35).

Name first appears on Wheeler Survey map (1878).

Peak was on the original 1946 HPS Peak List. Weldon Heald climbed this peak in 1942.