Dwight Whiting, who played a major role in the development of El Toro (Lake Forest), purchased the Serrano Adobe and a significant area of the rancho in 1884.

His son, George Whiting, made extensive additions to the dwelling in 1932, adding a dining room, bedroom, and kitchen.

Shortly after George Whiting's restoration effort, the Serrano Adobe was nominated and accepted as California State Landmark #199.

[3][4][5][6] Orange County set aside 4.1 acres (1.7 ha) surrounding the Serrano Adobe for the development of a historical park, now dedicated to interpreting the early history of the Saddleback Valley and El Toro area.

The Saddleback Area Historical Society formed in 1973 and supported the preservation of El Toro's first church, St. George's Episcopal Mission, and the first schoolhouse, the El Toro Grammar School, by moving these buildings to the Serrano Adobe site in 1976.