La Casa Primera de Rancho San Jose, Adobe residence in Pomona, United States.

La Casa Primera de Rancho San Jose is a single-story adobe house built in 1837 in Pomona, California, with five rooms and walls of thick adobe brick in the Mexican adobe style. It is the oldest home in the Pomona Valley and on the old Rancho San Jose land grant. The Historical Society of Pomona Valley restored it with period furniture and runs it as a museum.

The building was constructed in 1837 by Ygnacio Palomares on the Rancho San Jose land and represents the oldest structure in Pomona Valley. This adobe residence survived decades of California settlement and expansion to become a key record of that early colonial period.

Since 1973 the house has hosted folklorico celebrations with Spanish shawl displays, music and dancing. In 1987 it marked the 150th anniversary of the Rancho San Jose grant with Mexican dancers, strolling musicians, a parade of descendants of early Mexican families and a staged period wedding.

The Historical Society of Pomona Valley runs the adobe as a museum with period furnishings. The house sits on 1.7 acres in Pomona, and the grounds retain orange trees planted after 1867 plus remnants of a stone-lined canal of the Old Settlement Water Company. Contact the society before visiting to confirm opening conditions and access.

Francisco Palomares discovered the first artesian well on this property in Pomona Valley, leading to the establishment of the Old Settlement Water Company. This underground water source became essential to the area's future development and settlement.