While women represent nearly a third of the legal industry, only about 19 percent of partners at the nation’s law firms are female, according to an August study by the Institute for Inclusion in the Legal Profession.

The Washington market mirrors the nationwide underrepresentation of female lawyers in top-level jobs: 46 percent of associates in the District’s law firms are female, but only 20 percent of those firms’ partners are women — pointing to problems with retention and promotion rates.

“It’s a very demanding profession and it does take a toll to meet the expectations of partnership while taking the responsibilities of a family,” said Carol Clayton, assistant managing partner at WilmerHale, where a quarter of the partners are women.

WilmerHale’s ratio is one of the highest among large law firms, which Clayton attributes to mentoring and training programs and flexible paths for advancement within the firm.

“I’m hesitant to generalize...but some women end up with a disproportionate share of responsibilities at home and do opt out,” she said. “That’s a challenge for many of us.”

Industrywide, women have made slight but steady gains over the past decade. In 2000, women represented 29 percent of the profession; by 2009, that ratio had crept up to 32 percent. But women continue to be underrepresented at the top: nationwide, women comprise 19 percent of law firm partners, 27 percent of federal appellate judges and 21 percent of law school deans.

“We’ve seen our numbers slowly increase, as all law firms have over the years, but we need to do better and make sure there are opportunities for women to get promoted to partnerships,” said Marney Cheek, a partner at the District’s largest firm Covington & Burling who co-chairs the firm’s women’s forum, a professional development initiative that includes mentoring and programming geared toward the advancement of female attorneys.

Out of Covington’s 211 equity partners firmwide, 46 — or 22 percent — are female, among the highest in a recent American Lawyer diversity survey of top 100 firms.