California's 12th congressional district was vacated following the death of Democrat Tom Lantos on February 11, 2008.

[1] The special election was called by Governor Arnold Schwarzenegger to fill the vacancy for the remainder of Lantos's term ending on January 3, 2009.

[2] The special election took the form of an open primary.

Another election would have taken place on June 3 had no candidate received a majority.

The following individuals appeared in the certified list of candidates and the certified list of write-in candidates published by the California Secretary of State, and were thus eligible to receive votes in the special primary election.