The organizer of a so-called "tea party" in Pleasanton said it is one of more than 1,800 such events being held across the nation to protest higher taxes and increased federal spending.
Psychologist Bridget Melson said she expected about 2,000 people to attend the event, which runs from noon until 6 p.m.
Melson said the events, which are timed to coincide with the deadline for filing taxes, are aimed at calling for an end to any new taxes at the local, state and federal levels of government.
"We want the politicians to put a hold on new taxes and we want no more stimulus funding," Melson said.
Although the San Francisco event is sponsored by the Republican Party, Melson said the Pleasanton event is bipartisan and she wants Democrats, Republicans and independent voters to come together to fight against new taxes.
The tea parties are modeled on the original tea party in 1773, when American settlers who were angered over a British tax on tea boarded ships in the Boston harbor and dumped the tea cargo into the water.
In a play on words, organizers say "tea" stands for "taxed enough already."
Anti-tax groups also held a tea party rally at the state Capitol. Fox News anchor Shean Hannity is doing his show live from Sacramento today and it is expected to have the feeling of a ESPN Game Day event.
Democratic lawmakers have scheduled a Tax Day Reality Check news conference to talk about the budget cuts that California has made in recent years.
The demonstration comes as Republican Gov. Arnold Schwarzenegger and Democratic leaders are trying to convince voters to approve Proposition 1A. That's the measure on the May 19 special election ballot that would extend the sales and income tax increases the governor and Legislature approved in February.
They also cut more than $15 billion from state programs as part of a plan to close the state's $42 billion budget deficit.