The 11 guidelines include requiring vendors to stop providing alcohol 30 minutes before the end of an event and limiting the number of drinks a person can purchase to two at a time.
The new rules also call for checking the identities of anyone who appears to be under age 26, said Maria Reyes, senior director of Marin programs for the Youth Leadership Institute.
The guidelines were formed in part from the results of a survey of young people in the city, Reyes said.
The survey showed that 62 percent of youths had access to alcohol through social settings, including special events in the city, Reyes said.
Special summer events in San Rafael include the farmers' market and the Italian Street Painting Festival, Reyes said.
Officials planned to announce the guidelines at an 11 a.m. news conference at San Rafael City Hall. Mayor Al Boro and Police Chief Matthew Odetto were scheduled to attend.