The idea of the tipping point dates back to 1977, when Rosabeth Moss Kanter, then a professor at Yale University and Harvard Law School, theorized the idea of critical mass as it applies to women in positions of power. Kanter observed that women had to make up at least 30 percent of a team to contribute at their full potential. Under that threshold, women were often dismissed as token representatives of their gender—not equal participants, let alone persuasive decision makers. Ever since then, experts have debated the ideal proportion: Is it 35 percent? Would 25 be sufficient? Whatever the number, women in federal government haven’t reached it. “The point is to be included—not seen as an outsider,” says Kanter, now chair and director of Harvard University’s Advanced Leadership Initiative.

Make no mistake, it does help to have one woman, or a handful, in “the room where it happens.” That was visible in April, when Senator Tammy Duckworth (D–Ill.) gave birth to her daughter, Maile. Less than two weeks later she was back in the Senate, Maile in tow, for a vote. But Maile’s presence there—let alone her warm welcome— would have once been inconceivable. Babies have been banned from the floor as far back as all the people who serve in the Senate can remember. When Sen. Duckworth learned she was pregnant, she asked Senator Amy Klobuchar (D–Minn.) to lead a bipartisan effort to strike down the rule. For months Sen. Klobuchar met with colleagues to convince them to support a reversal. Some on the Hill were worried about whether—the horror!—Sen. Duckworth would have to breastfeed. But Sen. Klobuchar made her case, and the rule was overturned with unanimous consent. “I think it would do us good…to see a pacifier next to the antique inkwells on our desks,” said Senator Dick Durbin (D–Ill.) at the time.

Senator Tammy Duckworth, back at work with her newborn. CHIP SOMODEVILLA/GETTY IMAGES

It’s a nice sentiment, but it overlooks the fact that the United States remains the lone industrialized nation in the world that doesn’t guarantee paid parental leave. Kanter believes that more elected women would lead to changes in policies like paid leave or access to health care. But Georgetown University professor Michele Swers, Ph.D., is more skeptical. While she acknowledges that women have unique experiences to draw on that can make men view certain political issues with a fresh perspective, she cautions that women are not immune to the extreme partisanship that has infected Washington, despite the notion that women are reputed to be better at collaboration and risk assessment than men. “At the national level, there’s just less room for collaboration than there used to be,” Swers says.

Even so, women in the Senate have tried to make the most of their low numbers. It was former Senator Barbara Mikulski (D–Md.) who set out to boost women’s collective power with routine bipartisan dinners. Credit where credit is due, notes Sen. Murray: “Because we took the time separate from legislative action to know where people come from…then when those impasses are reached, it’s much more likely that someone will reach out and ask, ‘How can we solve this?’ ”

There’s evidence, too, that women in office use their voice to different effect than men. In a 2010 University of Minnesota study, researchers found that women in the House of Representatives give more floor speeches. (How else to be heard in public?) And female politicians tend to emphasize issues that matter more to women and families (never mind that most families include men too): A deep dive into 2018 congressional transcripts found that female representatives spent more than twice as much time on health care in their speeches as male legislators did. Those efforts could have a greater impact, in part, because of the “Jill Robinson effect.” Two political scientists coined the term in 2011, positing that because bias makes it harder for women to get elected, those who do persevere are more adept lawmakers. (The phenomenon is named after baseball icon Jackie Robinson, the first African American to play Major League Baseball.) To wit: The research found that congresswomen claim up to 9 percent more in flexible dollars for their districts than congressmen do. Want to better fund education or health care in your area? Elect women.

While business doesn't do much better than government when it comes to female representation— women make up just 21 percent of corporate board seats in the S&P 1500—active steps have been taken to boost their ranks. California recently passed bills that would require publicly traded companies in that state to have at least one woman on their board by 2020, and more women, depending on a company’s size, by 2022. Europe has had such requirements for a decade. In 2006, for example, Norway established a quota for women on boards. France now has one too; the aim for female representation is 40 percent. The laws were passed in the name of fairness, but they’re also good for business. A 2016 report from global nonprofit Catalyst found that companies with three or more women on their board of directors, no matter the size, outperformed the competition across three crucial metrics: return on equity, return on sales, and return on invested capital. In other words, money, money, money. And research from Miriam Schwartz-Ziv, Ph.D., assistant professor at Michigan State University, has found that members of gender-balanced boards are twice as active (meaning, likely to take initiative) as non-gender- balanced boards.

That math underscores principles that William P. Lauder, executive chairman of the Estée Lauder Companies, says have been baked into the DNA of his family’s business since its inception. In April the company added two more women, Jennifer Hyman, cofounder and CEO of Rent the Runway, and Jennifer Tejada, CEO of PagerDuty, to the board, which means eight of its 17 directors are now women. (For perspective, just three Fortune 500 companies have an equal number of male and female board members.) Lauder chafes at the excuse that there are too few qualified women candidates in the pipeline. Lauder, a member of the 30 Percent Coalition, an initiative to create more diverse corporate boards, maintains women are a “value add” for companies’ boards. Before beginning this latest search, he remembers he was explicit with his current board members: “I said, ‘Here’s what we need—we need expertise in cyber and we need expertise in social and digital.’ On top of that, I said, ‘We need more women directors.’ Those were the criteria: female, with these qualifications.”