At 4 p.m. each day, I stroll my one-year-old son to the nearest Central Park playground. While pushing him on the baby swings, I often chat with other mothers doing the same, exchanging children’s names, ages, and number of teeth. The conversation inevitably turns to what we did before spending afternoons blowing bubbles, singing “The Wheels on the Bus,” and preventing the ingestion of old leaves and puddle water.

“I used to be a lawyer,” I explain. And fairly frequently, the other mother says, “Oh, me too.”

These past-tense lawyers—women who leave large corporate law  firms, often in conjunction with having children—are nothing new. Though women make up 45 percent of associates in private practice, they represent only 20 percent of partners, according to statistics compiled by the American Bar Association. And the National Association of Law Placement Foundation reports that two-thirds of female associates will leave their firms within five years.

As described in a recent report from the University of California Hastings School of the Law, the flight of women from law firms is explained in part by the failure of traditional firms to deliver the flexible schedules that mothers—and most lawyers in general—want. Unlike older generations of working mothers, Gen Xers and Millennials have more of an expectation that work can and should sometimes yield to family time and other commitments.“Many [corporate] lawyers are able to be home at 7 or 8 to put their kids to bed, but then they log back on and are working until midnight,” says Lauren Pearlman, an attorney and the owner of Pearlman Career Counseling. “Sure, it’s flexible, but it’s not work-life balance.”

While traditional law firms offer some flexibility in theory, there’s really no release from the pressure to bill. The billable-hour model, under which productivity is measured by time spent on a project, creates an inherent conflict between the objectives of a firm and the objectives of a mother, or any lawyer who values time outside of work. From the firm’s perspective, a woman who can generate a stellar brief in time to make it to her daughter’s afternoon soccer game is less profitable than an associate who takes all night to complete the same task. “Moms are probably the most efficient workers in the marketplace,” says Erin Clary Giglia, the founder of Montage Legal Group. “But the way law firms are set up, that efficiency is not rewarded.”

The most common way mothers handle this conundrum is by taking on part-time schedules, but that comes with costs. “I don’t like feeling like I’m being sorted into a ‘not ambitious’ group. I’m swallowing my pride in order to take advantage of the opportunity to have a better work-life balance,” said one part-time associate at an elite New York firm. (She spoke to me on the condition of anonymity, because she was afraid of how her employer would respond to learning how she felt.) Many infer that having a child makes a woman less serious about work. “If a man’s office is dark on a Wednesday afternoon, people assume he’s at a closing. If a woman’s office is dark, people assume she’s at the playground,” says Debbie Epstein Henry, the president of Flex-Time Lawyers, a legal consultancy.

There are mothers who’ve made Big Law work for them after having children and many firms are eager to become more women-friendly. But for many new mothers, the downsides of practicing at a traditional, large firm outweigh the benefits—so they quit. The alternative, though—the transition from lawyer to full-time caregiver—can be fraught. Pamela Stone, a Hunter College sociology professor and the author of Opting Out? Why Women Really Quit Careers and Head Home, found that only 10 to 15 percent of high-achieving women who left the workforce actually intended to become stay-at-home moms.

“Mothers were the only demographic I interviewed who expressed remorse about leaving the law,” says Amy Impellizzeri, the author of Lawyer Interrupted: Successfully Transitioning from the Practice of Law—and Back Again.

But women who’ve been frustrated with the all-or-nothing decision may now have access to a middle ground. As detailed in the U.C. Hastings report, there are a number of “New Model” law firms created by and catering to women with children, which are tapping into the highly-qualified idle workforce of women who’ve left large law firms.

“We wanted to provide a way for women to have non-stigmatized, alternative careers,” says Epstein Henry, who co-founded Bliss Lawyers, a New Model firm that matches attorneys  with “secondment” assignments at corporations and law firms. Bliss pulls from a network of over 10,000 attorneys—which now includes men as well as women—she started to form in 1999 after struggling to balance her law career and family.

New Model firms let their lawyers select a schedule that works for them, without compromising the high-level nature of the work they desire. At a traditional firm, when a partner calls on a Friday at 6 p.m. with an assignment, an attorney has little choice but to cancel that weekend camping trip. But at New Model firms, attorneys have the power to say no. “I can do PTA, pick-ups, and drop-offs,” says Lindley Fraley, who takes on projects through the firm Montage Legal.

“These firms allow women to say ‘I’m still practicing law,’” says Impellizzeri. “The ability to hold on to that identity is huge.”

Mae O’Malley, the founder of the secondment-type firm Paragon Legal, is quick to point out that flexibility is not synonymous with scaling down. “Our attorneys are very much looking for a robust career with all the responsibility and high-level work that comes with that,” she says. “Often it’s just a matter of knowing they can leave at 5 p.m. to pick up a kid. This seems like such a simple thing to ask for, yet a it’s a privilege few attorneys enjoy.”

“There’s no question the demand for alternative firms is there,” says Pamela Stone. “What’s new is it’s no longer all supply-side from mothers. These firms are gaining acceptance and becoming less stigmatized because the demand is client-driven.” As the U.C. Hastings report emphasizes, clients see a significant value in hiring Big Law-trained attorneys from New Model firms for a fraction of Big Law rates.

While these firms are allowing women to resolve personal-professional conflicts, Stone worries they won’t alter the industry’s mainstream thinking. “These New Model firms are not getting women into the high-prestige, high-power positions in legal field. We don’t want to take the pressure off firms that are the shapers of the profession,” she says.

But New Model firms may help mothers who are looking for an alternative to Big Law find their work-life sweet spot. And maybe more women I meet at the swing set will tell me they are lawyers—present tense.