State Route 154 is a state highway in the U.S. state of California that runs from Los Olivos to Santa Barbara, crossing the San Marcos Pass in the Santa Ynez Mountains. Before U.S. Route 101 was built through the Gaviota Pass, SR 154 was the main throughway to Santa Barbara and the tri city area including use as a stagecoach route in early years. After being replaced by US 101 as the primary route between the Santa Ynez Valley and Santa Barbara, SR 154 now serves as a scenic bypass.

Los Olivos is an unincorporated community in the Santa Ynez Valley of Santa Barbara County, California, United States. Tourism is popular in this rural area which is an agricultural region with an emphasis on wine grapes. For statistical purposes, the United States Census Bureau has defined Los Olivos as a census-designated place (CDP). The population was 1,132 at the 2010 census. The ZIP Code is 93441, and the community is within the area code 805.