Somerville’s free street festival for the invention of Marshmallow Fluff turns 21 this year — Saturday September 19, 1–5pm in Union Square, with a severe-weather date of Sunday September 20. All ages, no ticket: more than 100 vendors, two stages, and the gloriously silly Shenanigans games.
More than 100 vendors selling fluff-themed food, art and merchandise, plus two performance areas: the Shenanigans Stage for the festival’s signature games and the Fluff ’n Jam Stage for live music, with pop-ups throughout.
This is the bit children remember: fluff musical chairs, fluff limbo, fluff jousting and the legendary fluff hairdo contest. This year’s theme is “Legally Fluff: A Toast to Union Square.”
Free and all ages, no ticket needed. Expect a crowd — organisers plan for roughly 30,000 people across the afternoon, so agree a meeting point with older kids before you go in.
Union Square, Somerville — Somerville Ave and Bow St between Church St and Union Square, plus the Union Square municipal lot. MBTA buses detour for the day and free bike valet runs at two spots on Somerville Ave.
Saturday, September 19, 2026, from 1pm to 5pm in Union Square, Somerville. The severe weather date is Sunday, September 20.
Yes — it is free and explicitly all-ages, with no ticket required. The Shenanigans Stage games are the main draw for children: fluff musical chairs, fluff limbo, fluff jousting and the fluff hairdo contest.
More than 100 vendors sell fluff-themed food, art and merchandise, and there are two performance areas — the Shenanigans Stage for the signature games and the Fluff ’n Jam Stage for live music — plus pop-ups throughout the festival. The 2026 theme is “Legally Fluff: A Toast to Union Square.”
Organisers expect roughly 30,000 people over the four hours, so it is genuinely crowded. Agree a meeting point with older children, and consider a carrier rather than a stroller for the youngest.
The festival runs on Somerville Avenue and Bow Street between Church Street and Union Square, plus the Union Square municipal lot. MBTA buses detour for the day, and free bike valet is available at two locations along Somerville Avenue.
Union Square Main Streets, a nonprofit, in partnership with the Somerville Arts & Culture Department as part of the ArtsUnion initiative. It has run since 2005 and celebrates Archibald Query’s 1917 invention of Marshmallow Fluff in Union Square.
📅 Planning the rest of the weekend? See what else is on in our family events calendar, or see everything in our Somerville kids’ activities guide.
Details from the City of Somerville and flufffestival.com.