The 1935-S San Diego commemorative half dollar honors the California-Pacific International Exposition, which took place in the southern California city of San Diego in 1935 and 1936. The coin, designed by Robert Aitken, was sold for $1 at the fair. Pieces struck in 1935 derived from the San Francisco Mint; more were made in 1936, and those come from the Denver Mint.

San Diego half dollars are among the most common of all classic commemoratives in part because large hoards of these coins were released from a few original purchasers during the 1970s and '80s. Most 1935-S San Diego half dollars are known in Gem Uncirculated condition, with pieces common through at least MS66. A small number of MS67s and a handful of MS68s also survive.