What the Fluff? A Tribute to Union Square Innovation is a madcap festival honoring the invention of Marshmallow Fluff, returning for its 18th year. It celebrates Somerville’s proud tradition of innovation with live music, fluffalicious feasts, sticky games, zany happenings, and much more.

Celebrate this iconic condiment with fellow Fluff lovers in Union Square, the longstanding home of this funky festival. This year’s theme Fluff Union: The Sweetest Square in Somerville showcases delightful and delectable tastes, sweet sights and sounds, incredible innovations, and community, sweet, community!  

Discover tasty local treasures at your favorite neighborhood businesses, raise a pint of Fluff with friends old and new, dance in the streets, and make sweet memories at the most flufftastic end-of-summer celebration in New England. 

Come by foot, bike, bus, or the Green Line subway stop for an unforgettable afternoon of adventure in a neighborhood brimming with discovery. Whether this is your first or 18th Fluff Fest, you’ll discover something new, wonderful, and unexpected in the Sweetest Square in Somerville—home to the most fluffalicious festival ever. 

Rain date: September 24, 2023