The Mallard (Anas platyrhynchos) is a year-around, widely distributed resident of California. It is known to breed at a great range of altitudes, from seacoast marshes to mountain lakes of the Sierra Nevada. Nests have been found as high as 1897 m (6225 ft) near Lake Tahoe (Grinnell, Bryant and Storer, The Game Birds of California, Univ. Calif. Press, 1918) and 2286 m (7500 ft) in Yosemite National Park (Grinnell and Miller, The Distribution of the Birds of California, Pacific Coast Avifauna No. 27, 1944). We have found no additional records indicating that Mallards breed higher than this in the Sierra Nevada. Therefore, we report herein our observations of a Mallard nest found in a subalpine meadow on the east side of Tioga Pass, Mono County, at an altitude of 3002 m (9850 ft).