Cole Ranch is an American Viticultural Area (AVA) located in Mendocino County, California. The small viticultural area was established on April 15, 1983 by the Bureau of Alcohol, Tobacco and Firearms (ATF), Treasury after reviewing the petition submitted by the proprietor of Cole Ranch in Ukiah, California. At less than a quarter of a square mile, it is the smallest appellation in the United States. The viticultural area is located in a small, narrow mountain valley west of Hwy 101 on the 500 acres (0.78 sq mi) ranch originally owned by the Cole family. The valley is approximately one mile in length and a half mile across at its widest point tucked into the high hills ranging from 1,400 to 1,600 ft (427–488 m) in elevation. The AVA is located between the Russian River and Anderson Valley. Several prominent wineries source grapes from Cole Ranch including Fetzer Vineyards and Chateau St. Jean. Cabernet Sauvignon, Merlot Pinot Noir and Riesling are the most popular planting. Cole Ranch viticultural area is sub-region of Mendocino AVA. As of 2024, the Sterling family, proprietors of the Esterlina Winery located at Philo, owns the vineyard acreage.