Hilltop Ranch Vineyard was established in 1905 by the Duggan family and was planted primarily in Zinfandel. After Prohibition was repealed in 1934, the vineyard and winery were re-bonded by Frank J. Duggan. It was advised to the most recent owners, John and Elizabeth Conely, that Hilltop Ranch Vineyard was the fourth vineyard in Sonoma County to re-establish and re-bond after 1934. The winery operation ceased around 1960, although the vineyard has continued to supply award-winning zinfandel grapes to several local Sonoma wineries, including Wellington and St. Francis Winery & Vineyards.