Winthrop Park became even greener than usual on Friday as Harvard Square celebrated the first-ever “Great Big Green Party.”

On Winthrop Street—adjacent to OM and Peet’s Coffee on JFK Street—swarms of party-goers celebrated Earth Week, picking up fliers, sampling food, and mingling with representatives from various local organizations.

Square restaurants had booths set up, as did the Charles River Conservancy and Green Streets, a grassroots organization that promotes environmentally-friendly transportation.

Visitors could also drop off unwanted computers, monitors, and cell phones for recycling at RE/MAX Destiny’s office around the street as part of the organization’s eco-wise realtor program.

Zipcar—the car-sharing service founded in Cambridge—was on-site as well, offering a discounted $25 annual membership.

Visitors had the opportunity to write “environmental sins” on Zipcar’s black Honda Civic Hybrid Chura, confessing activities that were less than green.

“I drive to the store even though it is close enough for me to walk to,” read one confession.

Boloco distributed biodegradable cups of compost made from the store’s organic waste filled with gardenia seeds.

And as any party is incomplete without hors d’oeuvres, attendees were treated to food samples including chilled honeydew melon soup from Henrietta’s Table and chips, salsa, and guacamole from Chipotle. Nantucket Nectars—a beverage company based in Nantucket, Mass.—gave out samples of all-natural fruit juices.

Wainwright Bank & Trust Company—a self-proclaimed socially-progressive bank with branches throughout Boston—was present to inform visitors about the bank’s green practices and to open new accounts.

The Harvard Square branch on Brattle Street—which has bamboo flooring, low-flow faucets and toilets, and low-energy heating and cooling—is currently awaiting Leadership in Energy and Environmental Design certification.

“It’s a great way to get people aware,” said Shoshi Stern-Robbins, a sixth grader at King Open School in East Cambridge.

She said that she tries her best to be environmentally-friendly and pushed her school to stop using Styrofoam lunch trays.

“It’s good to have a healthy environment and not have snow in April,” she said.

At 1 p.m., a clean-up kicked off in Winthrop Park, with volunteers picking up trash, sweeping sidewalks, and raking grass.

“It’s definitely a success,” said Harvard Square Business Association Executive Director Denise A. Jillson as she took a break from raking the grass. “I could certainly see this becoming an annual event.”

Aside from tourists, students, and Cambridge residents, the party also drew local luminaries.

“It’s fantastic,” said City Councillor Sam Seidel, adding that he rides a bike whenever possible and is upgrading aspects of his house to improve energy-efficiency.

“You can’t beat an event like this on a day like this,” he said.

—Staff writer Liyun Jin can be reached at ljin@fas.harvard.edu.