The 1857 United States Senate special election in California was held on January 13, 1857, by the California State Legislature to elect a U.S. senator (Class 3) to represent the State of California in the United States Senate. Legislators had previously attempted to elect a Senator in 1855, but could not reach a majority for a single candidate. In a special joint session, former Democratic Senator William M. Gwin was re-elected over Know Nothing State Senator Henry A. Crabb and Republican Nevada County District Attorney Aaron A. Sargent.