WASHINGTON — It’s said a first inauguration is like a wedding, a giddy celebration fueled by fresh possibility, infatuation and promise. The second is an anniversary, marked with nostalgia, clear-eyed expectations, maybe even a shrug.

The truism certainly holds for the Bridezilla-worthy bash that was Barack Obama’s first inauguration four years ago and the quieter, nice-dinner-out vibe of the second version that begins this weekend.

All the pomp is on the inaugural bill — the poet, the speech, the parade, the balls. But the planning committee has turned it down a few notches.

Instead of 10 official balls, the Obamas will attend two very large ones. There will be no whistle-stop-train tour delivering the guest of honor to Washington or battery of celebrities headlining a concert at the Lincoln Memorial. The official festivities begin Saturday with a national day of service; the inauguration theme is a decidedly un-Obama-centric “Our people, our future.”

The lower key is intentional. Second inaugurals never capture the energy of the first. There’s little point in trying to match the first inauguration of the first black president, even if his second swearing-in is also unprecedented. And then there’s the economic slump, organizers note.

“We want to be mindful of the economic times,” said Aoife McCarthy, spokeswoman for the Presidential Inaugural Committee.

The calendar has also conspired to undermine the drama. Because Jan. 20 falls on a Sunday, tradition dictates that Obama takes the oath that day in a private ceremony at the White House. The public ceremony Monday on the Capitol steps will be a bit of theater.

There will be plenty of parties and politicos rubbing elbows. Celebrities are flooding into Washington to headline balls. Democratic groups hope to use the event to rake in cash. Donors are coming to call in their chits. Volunteers and supporters are keen on taking a victory lap.

Still, no one is expecting 1.8 million people to fill the National Mall again. Hotel rooms were still available this week. Some Washingtonians hoping to make money renting out their homes have been disappointed. One of the unofficial balls — the Green Ball for the environmentalist crowd — offered discounted tickets on Groupon.

The White House, too, seems to be approaching the inauguration as more of a brief interlude for music and messaging than the start of a second term. For all practical purposes, that is well under way. Obama laid down his marker in his first big battle ahead, raising the debt ceiling, on Monday. On Wednesday, he announced his first policy priority — measures intended to reduce gun violence.

“Normally you win re-election and you have a few months for reflection,” said one administration official. “In our case, we had one day off, and then on Thursday we were running again.”

One White House aide has been very focused. Obama speechwriter Jon Favreau has worked on the inaugural address for weeks, working from the president’s handwritten drafts on yellow notepads. The White House has been mum on details, but presidential historian H.W. Brands notes there really is only one theme it can take.

“You have to sort of summarize and justify your first term, even as you say more work needs to be done. And that’s basically the theme of all second inaugural addresses,” said Brands.

Aside from the speech, Obama’s inauguration is finding ways to reinforce his first-term highlights. Organizers have assembled a committee of “citizen co-chairs,” a group of supporters, including many who benefited from the president’s policies.

The list includes an autoworker from Ohio who was laid off but went back to work after the bailout of auto companies, and Erica Chain, a San Franciscan who was diagnosed with a brain tumor and obtained insurance coverage through a government program created by the new health-care law.

“I feel so passionate about the mission,” Chain said. “To get the four more years was what we were all working for.”

Matea Gold and Christi Parsons

contributed to this report.