They came to share and hear their conservative point of view, and they got plenty of that from a host of Republican politicians and their representatives.
The biggest name at the Tea Party rally was Senate candidate and former Hewlett Packard CEO, Carly Fiorina.
"The people who create the American dream are not in Washington, they are here at this rally today," Fiorina told the crowd.
Meg Whitman sent a representative, as did a number of other Republican candidates.
The organizer of the event says she uninvited a woman who was scheduled to speak from the birther movement. Bridget Melson says fringe elements, including those who do not believe the president is an American citizen, do not belong there.
"I don't think we need to go so far right that we fall off the track there," she said.
Fiorina says it was not her campaign that called to complain about fringe elements from the radical right.
"What I see out here is a bunch of hard working Americans who care enough to come out and get politically active and express their views," said Fiorina.
"Any place there's a crowd you may get some fringe elements, but we've got thousands of people here who are reaffirming the ideals of the American founding," said David Harmer, who is running against Democratic congressman Jerry McNerney of Pleasanton.
Melson says her goal Thursday was to connect conservative mainstream politicians with voters.
"A lot of the Tea Party patriots I have heard want to form their own party, and I think that's a big mistake," said Melson. "Absolutely, a big mistake."
What difference the Tea Party could make in next November's elections is a question we asked ABC7 political analyst Bruce Cain.
"Does it represent 40 or 50 percent of the electorate? No. Can they win an election by themselves? No," he said. "But in the circumstance of a close election, an energized conservative base, whether a Tea Party base or a religious conservative base, can make a difference."