Over the objections of some fellow Republicans, Gov. Arnold Schwarzenegger signed a bill last year establishing May 22 as an annual holiday of sorts.
The measure simply encourages public schools to conduct commemorative activities in Milk's honor.
Only a handful of schools did that Friday. But rallies, concerts and fundraisers are among the Milk Day events planned for Saturday in California and 20 other states.
Milk was the first openly gay man elected to public office in a major U.S. city. He was serving on the San Francisco Board of Supervisors in 1978 when he was assassinated along with the mayor by a former colleague.