NEW YORK — As other protesters chanted vigorously around her, Nancy Pi-Sunyer stood off to the side at the Occupy Wall Street rally, clutching her sign, looking a little like a new teacher on the first day of school.

In a way, she was: At 66, this retired teacher was joining a protest for the first time in her life.

“I was too young for the civil rights movement,” Pi-Sunyer said earlier this week as she joined thousands of protesters marching in lower Manhattan. “And during the Vietnam War, I was too serious a student. Now, I just want to stand up and have my voice be heard.”

As the protests have expanded and gained support from new sources, what began three weeks ago as a group of mostly young people camping out on the streets has morphed into something different: an umbrella movement for people of varying ages, life situations and grievances, some of them first-time protesters.

There are a few common denominators among the protesters: their position on the left of the political spectrum, and the view that the majority in America — the “99 percent,” in their words — isn’t getting a fair shake.

Beyond that, though, there’s a diversity of age, gender and race — in part due to the recent injection of labor union support, and fueled by social networks — that is striking to some who study social protests.

“Most people think this is a bunch of idealistic young kids,” said Heather Gautney, a sociology professor at Fordham University and an analyst of social protests. “But the wider movement is remarkably more diverse than it’s been portrayed. I’ve seen a lot of first-time protesters, nurses, librarians. At one protest, the younger element seemed actually to be in the minority.”

Pi-Sunyer, who lives in Montclair, N.J., was drawn into the fray Wednesday the same way many were — via social networks. She saw a post from a friend on Facebook and realized it was time to join.

“I just decided to get off the couch and be in control,” she said, holding a hand-lettered sign that read: “Wise OWLS Seek Economic Justice 4 All.” (OWLS was a play on the initials for Occupy Wall Street — with an “l’’ for little people.) “I was oblivious before. I can’t be oblivious now.”

Nearby, a speaker in Manhattan’s Foley Square yelled into a microphone: “I’m tired of sticking my hand in my pocket, and only getting my leg!” The so-called “Granny Brigade” pulled out guitars and played a song. The crowd milled, bearing an endless variety of signs:

“Make Banks Pay!” “Corporate Greed is Not Patriotic!” “Give My Professor Health Insurance, Please!” “Food is A Basic Human Right!” “Bernanke Burnout!” An optimistic one: “This Is The First Time I’ve Felt Hopeful In a Long Time!” And a pessimistic one: “Even My Union is Corrupt!”

Cherie Walters, 58, also a former teacher, had driven all the way from Michigan with her husband, Rich.

Her biggest gripe: credit card swipe fees, which she said are killing smaller businesses. She also was concerned about unemployment in her state. “I’m very angry at how poverty is degrading our people,” she said.

Such diversity is what organizers were hoping for, said Patrick Bruner, spokesman for Occupy Wall Street. Since launching the protests in mid-September with a group of mostly young activists, “we’ve made a concerted effort to diversify our group,” he said, with an outreach committee and caucus groups for people of color, for example, or for women. “We’ve gradually seen our message resonate with different groups of people.”

Organizers also have been encouraging people to tell their stories in a virtual protest on tumblr, the social network, spotlighting people of different backgrounds, each tale of economic hardship ending with: “I am the 99 percent.”