The Naming of Oakland occurred on March 2, 1855. For post office purposes, prior to that it was known as Contra Costa.

According to The Beginnings of Oakland by Peter T. Conmy, Horace Carpentier had been employed by the legislature, and knew of the work of General Mariano Guadelupe Vallejo in explaining the meaning of place names in California. Asked to name the town, he looked into the Spanish "encinal" (oak grove) and suggested it be called Oakland.