Originally from the Tulsa suburb of Owasso, Okla., Ross learned to use cookbooks at an early age. As the only vegetarian in her family, she prepared her own meals out of a copy of The Moosewood Cookbook her mom had bought her. She spent her later teenage years in New York before heading to Boston's Northeastern University to study sign language.
She decided to leave school and held a variety of seasonal jobs - whitewater rafting guide in Oregon, day-care specialist in Deer Valley, Utah - before taking an extended trip to Europe that cemented the epicurean half of her current career.
"That's where I learned about food," said Ross, who had the opportunity to take cooking classes and eat at Michelin-starred restaurants in multiple countries.
Returning to the States, Ross spent three years as a librarian in Charlotte, N.C., and resumed her sign-language studies. She came here after her boyfriend at the time's job transferred him north.
She'd barely unpacked before wandering into Reading Terminal Market.
Ross' nose for spines led her to a help-wanted sign at The Cook Book Stall, which original owner Nancy Marcus opened in 1983. "I think I scared her," said Ross of the sure-of-herself pitch she presented to Marcus. "I said, 'I'm Jill, I just moved into town, and I'm the girl that wants to work here.' "
That got her the gig, and a year later, she purchased the Stall from Marcus, who had been looking to sell. As she settled in, Ross looked to make inroads with one group she knew she could count on for regular business: local kitchen staffs.
"I really got out there and met a lot of chefs," said Ross, who developed a reputation for fielding very specific and obscure requests for European books and magazines.
"She would get all the ones no one else carries. She would call [Montreal Chef] Martin Picard up and get [his Au] Pied de Cochon book, before anyone knew what the hell Pied de Cochon was," said Matthew Ridgway, chef and owner of The Pass in Rosemont, N.J. Early in Ross' tenure at the Stall, Ridgway worked as chef de cuisine of Lacroix at the Rittenhouse. He passed along word to his cooks and chef friends that Ross was a valuable resource.
"I told all my guys, if you want to learn about cuisine, you have to start reading," said the chef, who owns around 1,300 cookbooks himself. "This is where a lot of our learning took place. It's important for chefs to read. Jill saw that and became a cookbook maven."
Ross also counts local chefs like Marcie Turney and Konstantinos Pitsillides among her regular customers. She cherishes these local connections, even if roughly 60 percent of her business is tourists and out-of-towners.
"I like to have something for them to come back and see," she said. "They're not my bread and butter - they're my Champagne."
To complement the roughly 3,000 hard-copy choices available at the Stall on any given day, Ross launched a website ( thecookbookstall.com) earlier this month.
Online, she offers a lineup of around 1,100 books, a selection that includes both rare international titles and popular Philly releases, like Osteria chef Jeff Michaud's Eating Italy.
There's also a section of to kid-friendly picks from Ross' 7-year-old son, Emerson, whom regulars have watched grow up behind the counter.
Personalized curation, both in the brick-and-mortar shop and on the web, is what Ross hopes sets her business apart from the Barnes & Nobles and Amazons of the world, along with her willingness to hunt down elusive finds.
"If the book is still in print and still available, I will find it and get it for you," she said.
The print industry has taken plenty of pummeling over the last decade, but Ross regularly witnesses firsthand that "the passion for books is still there."
"People who like books still buy books. I'll have people come in and say, 'I need another cookbook like I need a hole in my head!' And then walk off with a stack of them."
The Cook Book Stall, Reading Terminal Market, 1100 Filbert St., 215-923-3170, thecookbookstall.com.