When Joanne Cooper was asked to arrange a time to discuss Mobilia, the craft gallery she runs with her sister in Cambridge, Massachusetts, she handed the task to her sister, Libby. “She’s much better with scheduling,” she explains.

Libby Cooper also handles pricing and the rest of the business side. JoAnne says that’s also not her strength. “But I love performing and speaking, so when we have an opening reception, I’m the one who talks about the work and gives tours – whereas Libby has these visions for displaying work that are amazing.”

Together, they decide on exhibitions and installations. The gallery, which turns 40 this year, benefits from the sisters’ complementary skills and from their unified vision. “We both have the same kind of tastes, and we collaborate on everything,” JoAnne says.

The sisters, who grew up in the Boston suburb of Newton, were raised by contemporary art collectors. “Our parents used to take us on studio visits to different artists, and when we were older they let us choose some of the pieces,” says Libby, older by a year. “Our mother always encouraged our art. She painted and drew with us and made tiles out of our drawings.”

Libby’s first job, at Design Research in Cambridge, one of the country’s first stores devoted to modern furnishings, added to her design and retail experience. She went out on her own with a pushcart in the justopened Faneuil Hall Marketplace in Boston in the late 1970s, and in 1978, she opened Mobilia. Ten years later, it landed in its current space in Huron Village, a picturesque residential neighborhood a mile and a half west of Harvard Square.

JoAnne majored in painting and ceramics, studying in California and Massachusetts, then took her love for art down a less conventional path, working as a Mardi Gras face painter in New Orleans and a makeup designer for a show in Las Vegas. She joined Mobilia in 1990.

Over the phone, it’s difficult to figure out who is talking. They sound alike and finish each other’s sentences. Both also know their roster of artists, which hovers around 100. Some have been with Mobilia since the early days, such as 2016 MacArthur Fellow Joyce J. Scott, known for her jewelry, beadwork, and glass. “We have a necklace from when she first started out,” says Libby. Mobilia is staging a comprehensive solo show of Scott’s work later this year as part of a series of 40th-anniversary events.

Although the sisters say they don’t emphasize one particular medium, the gallery is known for art jewelry – which Libby and JoAnne also love to wear. Their first criterion for choosing work: They must react with “Wow, look at this!”

Beyond suiting the sisters’ tastes, the creator must have “brilliant technical skills,” Libby says. “We want to see a lot of thought and a passion and vision behind their work. We’re always looking for new techniques and materials.”

They want to make sure the gallery itself has a strong visual impact – “the ‘ooh and aah’ factor,” she says. “We want it to be calm, but also exciting, with a museum feel.”

The sisters work with collectors and museum curators to place artists’ work. In 2016, they started the Design Store on their website to reach online buyers. Libby figures that the online shop is Mobilia’s most radical change in four decades. “It’s a work in progress, but we love doing it because it expands the audience for our artists.”

The sisters also entertain customers every Saturday at their “Picasso and Pie” receptions, for which they prepare and serve snacks inspired by the art or made using artists’ own recipes.

Some business owners of a certain age would be eyeing retirement, but the sisters have no desire to slow down.

“We’re having too much fun to stop,” says JoAnne. “Our family lives into their 90s, so we just plan to keep on going.”