The Petaluma Adobe State Historic Park is a state park and historic site in Petaluma, California. It was created as a means to preserve the California and National Historic Landmark known as the Rancho Petaluma Adobe.

The focal point of the Petaluma Adobe State Historic Park is the main historic ranch house built in 1857. It was owned and constructed by General Mariano Guadalupe Vallejo who was the commandant of the Sonoma Pueblo. The house is the largest example of the Monterey Colonial style in the country and about 80 percent of the current structure is made of the original materials used to build it initially.

Today, visitors of the Petaluma Adobe State Historic Park can enjoy picnicking and touring the old ranch house and surrounding areas.