The What the Fluff? Festival takes place this Sunday from 3:00 to 7:00 p.m. in Union Square.

Update: What the Fluff? Festival has been moved  to the rain date, Sunday, September 24 from 3-7pm

What the Fluff? A Tribute to Union Square Innovation returns for an 18th year this Sunday, September 24 from 3:00 to 7:00 p.m.. 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.

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 presented by Boynton Yards – showcases delightful and delectable tastes, sweet sights and sounds, incredible innovations, and community, sweet, community.

Discover tasty local treasures at 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. Just like Union Square, there’s something for everyone with a wide variety of themed happenings which promise cost-free fun for all ages:

Take part in hilarious antics with sticky activities like Fluff Musical Chairs, Fluff Limbo, Fluff Hairdos, and Fluff Jousting on the Shenanigans Stage hosted by Fluff Fest’s longtime Archibald Query impersonator

Groove with Emcees Sheila and Bobby Foley, of The Neighborhood Restaurant and Bakery and DJ Paul Casserly of Reliable Market on the Fluff’n Jam stage featuring:

Special Welcome from Mayor Ballantyne at 3:00 p.m.

FM Collective at 3:15 p.m.

Oom Yung Doe demo at 4:00 p.m.

Samba Cisse & Silimbo D’Adeane at 4:20 p.m.

Grace Givertz at 4:45 p.m.

Villari’s Martial Arts demo at 5:25 p.m.

Samba Cisse & Silimbo D’Adeane at 5:45 p.m.

Mayor Joe Flufftastic Innovation for Impact Award presentation honoring Bill Cavellini and Michèle Hansen, Union Square Neighborhood Council founding co-chairs at 6:00 p.m.

The White Owls at 6:15 p.m.

Get inspired at Innovation Alley presented by Somernova featuring youth inventors at the robotics ring, fresh ideas on the freeform mic, and chances to relax at the Inno Alley Lounge.

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 of your favorite Fluff characters by local artists Nathaniel Devarie and CultureHouse.

Snag your Fluff shirts, tanks, sweatshirts, koozies, tote bags, and more at the Fluff Stuff merch booth underwritten by The Goods.

Browse more than 60 vendors ready to serve up sweet and savory Fluff-inspired dishes, oodles of Fluff-themed items, community groups, and crafts.

Shop scores of local businesses who will be opening 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.

For those who know Union Square, Fluff Fest is a beloved tradition that marks – in all its zany glory – the arrival of fall,” said Jessica Eshleman, executive director of Union Square Main Streets. “For those just discovering our neighborhood, What the Fluff? offers an incredible spectrum of unexpected opportunities to fall in love with the locally-owned businesses that make our corner of Somerville so unique and spirited.” 

The endlessly entertaining What the Fluff? Festival is made possible by the generosity of its sponsors: Boynton Yards, Somernova, The Goods, The Hamilton Company, Rockland Trust, Holiday Inn Boston Bunker Hill, USQ, Kerbey Harrington Pinkard LLP, Citizens Bank, Liberty Cannabis, Verizon, EventThem, CultureHouse, Parkour Generations Boston, MassBike, Thalia Tringo & Associates Real Estate, Feast & Fettle, Middlesex Federal, HomeWorks Energy, Nicewicz Family Farm and Naveo Credit Union.

Festivities are expected to attract 20,000 Fluff fans and traffic will be rerouted around Union Square to accommodate festival activities. Revelers are highly encouraged to walk, bike, boogie, or take public transit. Green Line riders will be provided with free, fully accessible shuttles from the East Somerville stop to the heart of Union Square running approximately every 10 minutes. 

For a second year, free bike valets will be offered by Mass Bikes. Bike valets can be found on Somerville Avenue at the eastern festival entrance near Gracie’s Ice Cream and the western entrance near Market Basket.

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

Date:  Sunday, September 24, from 3:00 to 7:00 p.m. 

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

More details: www.flufffestival.com.