What the Fluff? A Tribute to Union Square Innovation presented by The Boston Globe’s Camberville & beyond returns for the 20th year this Saturday, September 20 from 2pm to 6pm (severe weather date 9/21). This zany, madcap festival honors the invention of Marshmallow Fluff by Archibald Query in Somerville in 1917 and salutes the spirit of innovation that thrives throughout the city today. 

Every September since 2005, Marshmallow Fluff has taken over Union Square to instigate all kinds of sticky situations. That’s 20 wild, wacky, sweet years of artists, businesses, and community coming together in the name of Fluff. This year’s theme, Forever Fluff: 20 Years of Sticky, Sweet Somerville, commemorates the endurance of this endlessly unique and unexpected celebration.

If anything’s proved true over these 20 years, it’s that folks don’t Fluff around for just one day. Fluff tattoos? Been there. Fluff “I dos”? Done that. In Somerville, Fluff is so much more than just a culinary confection–it’s a time-honored tradition. 

Festival-goers love to devour deliciously diverse food, shake it alongside toe-tapping performances, feud in family-friendly games, visit with 100+ vendors that know what Fluff is all about, and explore Union Square which was named the 38th coolest neighborhood in the world last fall. 

Whether this will be your 1st, 5th, or 20th Fluff Fest, Forever Fluff has something for Fluff fans of all ages:

• Take part in hilarious antics with sticky activities like Fluff Musical Chairs, Fluff Limbo, a Fluff Hairdo Contest, and Fluff Jousting (yes, jousting!) on the Shenanigans Stage and hosted by Fluff Fest’s longtime Archibald Query impersonator

• Groove with emcee Saba Wahid Duffy of Kush by Saba on the Fluff ‘N Jam Stage, with electric performances from: Wyn + The White Lights, Paul Willis, YellowShed, and Grooversity 

• Honor this year’s Mayor Joe Flufftastic Innovation for Impact Award honoree, Fluff Fest Founder and Fluff: The Sticky Sweet Story of an American Icon author, Mimi Graney  

• Get inspired at Somernova’s Innovation Alley where ideas stick, robots roam, marshmallows tower, and attendees enjoy hands-on fun

• Challenge yourself or friends to navigate a flufftastic parkour course hosted by Somerville pros Parkour Generations Boston 

• Try your hand at old-school, boardwalk-style games including Fluff Bowling, Fluff Ring Toss, and more at the Midway Games Area (free to play, free to win prizes) 

• Strike a pose with colorful cutouts and cocreate a community paint-by-number masterpiece of your favorite Fluff characters by local artist Nathaniel Devarie 

• Snag your official Fluff Fest merch: t-shirts, sweatshirts, trucker hats, koozies, stickers, tote bags, and more at the Fluff Stuff merch booth

• Browse 100+ vendors whipping up sweet and savory Fluff-inspired dishes, creating oodles of Fluff-themed items, and connecting festival-goers with the vital work of community groups who serve Somerville’s diverse community 

• Shop scores of local businesses who open their doors to Fluff lovers in the lead up and during the Festival for you to enjoy scrumptiously sticky treats, buy limited edition Fluff goodies, and take advantage of other flufftastic specials. 

“Twenty years of Fluff Fest is so much more than just a sweet, rocking good time – it celebrates what makes Somerville unique,” said Jessica Eshleman, Executive Director of Union Square Main Streets, the nonprofit who produces the festival in partnership with the Somerville Arts Council. “Innovation, the arts, small businesses, and strong community connections are what make Union Square the place to be on September 20.”

The endlessly entertaining What the Fluff? Festival is made possible by the generosity of its sweet sponsors: The Boston Glove’s Camberville & beyond, GBH, The Hamilton Company, Somernova, EventThem, Kerbey Harrington Pinkard LLP, Liberty Cannabis, Rockland Trust, USQ, The Goods Cannabis, Coast Cannabis, Cambria Boston Somerville, Life Alive, Middlesex Federal, Nicewicz Family Farm, Raising Cane’s, Renewal by Anderson, MassBike, Parkour Generations Boston, Confetti Friends, Parenting Journey, The Durkee-Mower Company, and Teddie Peanut Butter. 

Free bike valets by MassBike can be found on Somerville Avenue at the eastern festival entrance near Gracie’s Ice Cream and the the western entrance near Market Basket. 

What the Fluff? is produced by Union Square Main Streets and the Somerville Arts Council.

• Date:  Saturday, September 20, 2025 from 2pm to 6pm / severe weather date Sunday, September 21 

• Where: Somerville Avenue from Warren Street near Gracie’s Ice Cream to School Street near Market Basket in Union Square, Somerville, MA 02143

• Cost: Free!  

• Fluff details: www.flufffestival.com