This weekend, Philadelphia Brewing Co. will host the region’s first vegan beer festival. Yes, we know what you’re thinking: Isn’t all beer vegan?

No, or they wouldn’t have to hold a festival.

“More and more of our customers are identifying as vegetarian or vegan,” Philadelphia Brewing co-founder William Barton said. “Although most non-vegan beers are easy to spot, most beer drinkers are unaware of the fairly common practice of using animal-based ingredients [in beer]."

While all of Philadelphia Brewing’s beers may be vegan, many breweries, Barton said, employ animal-based additives to get the clarity, flavor, and body they’re looking for in a particular brew.

Isinglass, for example, comes from the bladders of fish, and is used as a fining agent to help filter yeast out of finished beer. Gelatin, which is derived from cows and pigs, also helps to remove haze from finished beer, as does the milk-derived protein casein.

On the flavor and mouthfeel side, ingredients like lactose (a milk sugar used in milkshake IPAs, milk stouts, and other brews) and honey disqualify many beers from being considered vegan.

Vegan beer-drinkers might not even know their chosen brew doesn’t fit with their cruelty-free lifestyle. Brewers are not required to list their beers’ ingredients on packaging. However, some resources, such as Barnivore, help vegans verify the animal-friendly veracity of their favorite brews.

“We have never used these clarifying agents in the production of our beers and invested in a top-notch centrifuge many years ago,” Barton said. “More recently, we invested in new equipment and a new, lactose-free recipe for our beloved Joe Coffee Porter made with locally roasted Passero’s coffee.”

Dubbed Vegan Beerfest, Philadelphia Brewing’s inaugural vegan beer festival will take place at the company’s Kensington headquarters (2440 Frankford Ave.) on Saturday, July 20. The pay-as-you-go fest will highlight Philadelphia Brewing beers. Vegan-friendly food will be provided by chef Jen Zavala, Martha, Philadelphia Brews Creamery, Witching Hour Sauce, and Chocolates by Kevan.

Vegan beer-lovers can can enjoy vegan beer and food in Philadelphia Brewing’s indoor bar area, known as the Peacock Room, as well as their outdoor beer garden from 12 p.m. to 4 p.m. To go along with the fest’s vegan offerings, attendees can expect to find lawn games, live music, and adoptable dogs courtesy of Morris Animal Refuge.