The First Friday block party has long been a fixture of St. Petersburg’s thriving downtown social scene.

Now Tampa is poised to launch its own monthly social happening, focused mainly on the museums and theaters that run the length of the city’s Riverwalk.

Fourth Friday starts Friday in downtown Tampa with nine cultural venues planning afternoon and evening events and more than 15 bars and restaurants offering deals ranging from discounts to extended happy hours. Free water taxi rides will be available to enable revelers to hop from venue to venue.

Tampa is pitching its event as a little more sophisticated than St. Petersburg’s monthly drinkfest. It will have a focus on Tampa’s growing cultural and arts scene, and organizers hope it will draw more people downtown and through museum and theater doors.

“The arts and culture scene in Tampa is growing; it has become very rich,” said Donna Chen, director of marketing and communications for the Tampa Downtown Partnership. “What better way to tell that story than to have a monthly event like this that puts the spotlight on these institutions.”

Organizers anticipate visitors will park their cars and use water taxis and bike rentals to navigate downtown. Their first move will be to pick up a free wristband to qualify for water taxi rides and to take advantage of special offers in participating restaurants and bars.

Among the events billed for the inaugural Fourth Friday are free admission and tours at the Henry B. Plant Museum from 4-5 p.m. There will be free guided tours and food at the Florida Museum of Photographic Art between 4 and 7 p.m., and the pay-as-you-will admission fee at the Tampa Museum of Art buys docent-led tours of Jaume Plensa’s “Human Landscape” sculptures. The Straz Center is offering a free outdoor performance by singer-songwriter Francesca Ani.

The Tampa Bay Rays and the Tampa Bay Lightning will have promotional booths and activities set up in Curtis Hixon Waterfront Park, Chen said. The Florida Aquarium also is participating.

The impetus for the event came from a handful of museums that already promote one another’s venues and coordinate events.

Leaders of the museums approached the Tampa Downtown Partnership and suggested that the event be expanded. The partnership worked with the venues on branding the event.

“We tried to create this momentum,” said Zora Carrier, executive director of the Florida Museum of Photographic Art. “The last thing we wanted to do was to create an environment of competition, so we choose the fourth Friday.”

Carrier said the event gives museums and theaters a way to give back to the community by helping local bars and restaurants.

Having a regularly scheduled event makes it easy to market because visitors quickly learn to add the day to their social calendars, Carrier said.

With all nine cultural venues working to market the event, they are able to reach and share new audiences. She expects the event will bring double the roughly 125 people who attend new openings or talks by artists.

“It’s really easier to market something that has tradition and regularity,” Carrier said. “If someone is already a fan of visual arts, there is a pretty good chance they’re interested in music or theater; we get a better opportunity to share these visitors.”

First Friday in St. Petersburg is centered around Central Avenue between Second and Third streets, with live music and revelers spilling onto the streets.

The event is a big draw for crowds, with business increasing by up to 50 percent over a regular Friday, said Chris Hamilton, general manager at Café del Mar, a gastro lounge on Central Avenue that has sponsored the event for four years.

“It makes sense,” he said. “The days surrounding it are usually a lot slower. I think everyone waits for First Friday to come out.”

Alcohol is likely to be part of the Tampa event, too, since the city in 2014 passed an open-container ordinance that allows eight venues licensed to serve alcoholic beverages along the Riverwalk to provide drinks in city-approved disposable cups bearing the Riverwalk logo.

Chen said the event has been put together with virtually no budget. A local Web designer built a website free. Social media are being used to market the event.

The museums and theaters taking part have committed to running the event for a year, Chen said, but the plan is to make it a permanent part of the city’s social fabric.

“We believe we’ve got a hugely successful recurring program,” she said. “It truly makes for a big-city experience.”