This wacky, one-of-a-kind festival honors the invention of Marshmallow Fluff by Archibald Query in Somerville in 1917 and salutes the spirit of innovation that still thrives in Union Square today. Now in its 21st year, the What the Fluff? Festival showcases clever culinary creations, live music and entertainment, and incredible artistic innovations brought to life by more than 100 local businesses and participating vendors.
Raise a glass to Union Square as What the Fluff? turns 21! This year’s theme – Legally Fluff: A Toast to Union Square – is an ode to 21 years of fluff-filled fun for all ages. Put on the party hats, blow up the balloons, grab a bubbly bev, and celebrate Somerville’s signature sweet spread in style. Prost! Sláinte! ¡Salud! Here’s to Union Square!
What the Fluff? is brought to you by Union Square Main Streets with a mission to preserve the unique character and advance the strength of the Union Square business district and community in partnership with the Somerville Arts and Culture.
Please stay tuned for event details, location updates and more!
Severe weather and other emergencies can happen. Fluff Festival attendees can sign up for day-of emergency text alerts for this year’s event: text FLUFF26 to 888777.
Road Closures and Restrictions
The event will be held in and around Union Square and will include the following road closures, traffic modifications, and event areas:
Road Closures from 10 AM to 7 PM:
- Somerville Avenue, from Church Street to Union Square
- Bow Street, from Union Square to Church Street
- Union Square Municipal Lot
Access restrictions from 10 AM to 7 PM:
- Vehicles on Bow Street Place will not have access to or an outlet on Bow Street.
- Vehicles on Kilby Street will not have access to or an outlet onto Somerville Avenue.
Vehicular traffic will be detoured from 10 AM to 7 PM:
- Stone Avenue – no access from Somerville Ave
- Warren Avenue – no access to and from Bow St
- Walnut Street- no access from Bow St
- Wesley Park- no access from Bow St
- Summer Street no access from or to Bow St
- Vinal Ave no access to Bow St
- Carlton Street no access to Somerville Ave
- Hawkins Street no access to Somerville Ave
- Webster Ave no access to Bow St
Parking Restrictions will be in effect from 9 AM to 7 PM:
- Both sides of Somerville Avenue, from Church Street to Union Square
- Both Sides Bow Street, from Union Square to Church Street
- Union Square Municipal Lot
Accessible Parking from 10 AM to 7 PM
- Add 4 accessible spots on Somerville Ave closest to Church St
Temporary Two-Way Access from 10 AM to 7 PM
Abutters to Giles Park or Hillside Park may use Walnut Street at Columbus Avenue as a two-way street for property access only, please proceed with caution.
Hawkins Street, between Somerville Avenue and Lake Street, may be used as a two-way street for abutter access only, please proceed with caution.
Stone Ave may be used as a two-way street for abutter access to Stone Avenue and Stone Place only, please proceed with caution.
Accessibility Needs:
Persons with disabilities who need auxiliary aids and services for effective communication (i.e., CART, ASL), written materials in alternative formats, or reasonable modifications in policies and procedures in order to access the programs, activities, and meetings of the City of Somerville should contact the ADA Coordinator in advance at 617-625-6600 x 2059 [email protected].
The City of Somerville can provide you with an interpreter in your language for free. To request an interpreter, please contact us at [email protected] or call 311 (617-666-3311) at least 7 days in advance of this event.
When
Saturday, September 19, 2026
1:00pm – 5:00pm
Where
Map UnavailableSomerville Ave between Church St and Union Sq
52 Union Sq
Somerville, MA 02143