Correction, 1/3/12, 11:40 a.m. EST: The print edition of this story incorrectly stated that Gibson, Dunn & Crutcher had four women on its 15-partner executive committee in 2001. The firm had four women on this committee in 2011. The 15th paragraph of the story has been revised to reflect the correct information. We regret the error.

Our question was simple. After years of measuring women’s success in law firms primarily by the percentage of female equity partners, we wanted to use a more exacting standard. We wanted to know: How many women partners had advanced to the highest ranks of law firm hierarchies?

To that end, we asked each firm in The Am Law 100 to list the women partners serving in their firm’s highest leadership positions—as firmwide managing partners or chairs, as members of a chief governing body or a compensation committee, as head of a practice or an office. After a fair amount of pestering, 93 firms in The Am Law 100 responded. Their answers were not surprising. There was a smattering of firms that stood out for their higher proportion of women in top leadership roles—a group that included Fulbright & Jaworski, Reed Smith, and Shook, Hardy & Bacon. These outliers had female partners who represented more than a third, or even half, of a governing or compensation committee, and they did so with a critical mass of three or more seats. But for most of the rest, the numbers of women leaders were depressingly similar.

As our in-depth interactive chart shows, it was a tale of ones and twos among many of the chief governing committees. Almost 80 percent of the 92 firms with a chief governing committee reported a committee with two or fewer women; 42 percent reported a committee with only woman partner. (Eight firms, including Bryan Cave, Cahill Gordon & Reindel, Chadbourne & Parke, Davis Polk & Wardwell, Lewis Brisbois Bisgaard & Smith, Morgan, Lewis & Bockius, Proskauer Rose, and Wachtell, Lipton, Rosen & Katz, had at least one chief governing committee with no women partners.) There were a handful or two of female managing partners or chairs. And women were rife among professional development, diversity, recruiting, and partner nominating committees. But they were in far shorter supply when it came to the very top power structures of the firm—the select groups that chart each firm’s strategic course, policies, and, of course, their pay. Membership among these governing groups isn’t the only mark of power at law firms, of course, nor are these positions necessarily sought or desired by all partners. But the visibility and influence of these leadership groups is difficult to dismiss. And the relative dearth of women in these top roles is striking. As one female partner at an Am Law 100 firm put it bluntly: "Women are largely getting stuck in lower middle management. There is still a moat around the top management, and that keeps the power to a small group of men."

The reasons offered by partners and law firm leaders are, in part, familiar: that there aren’t enough senior women partners or rainmakers to populate these positions. Some argue that women turn away from the time and administrative burden of these leadership positions; others minimize their significance in the relatively flat hierarchies of law firms. Almost all raised a theory of law firm relativity: We know that we should have more women in leadership positions, but we’re no worse than our peers.

Against this backdrop, the firms that have a more meaningful proportion of women leaders are all the more noteworthy. And while there is no simple formula, a combination of management will, a focus on succession planning, and partnerships with clients have yielded admirable results.

The broad spectrum of management and governance structures among The Am Law 100 makes side-by-side comparisons challenging. Some firms have only one governing body, others have two or more, and a few have none (Cravath, Swaine & Moore and Quinn Emanuel Urquhart & Sullivan). The titles and responsibilities vary, but as a group, the most common entities include some combination of a management committee, an executive or policy committee, and an executive or advisory board. To simplify, we collected the gender data for each firm’s "primary governance committee," allowing firms to name up to two committees if they were of roughly equal power and importance. For consistency, we listed the smallest committee first when firms reported two committees. We also compared the gender data for the group charged with making partner compensation decisions. In some cases this was a separate compensation committee; in others it was identical to one of the firm’s chief governing bodies or a subset of one. (We always listed the group responsible for compensation decisions separately in our chart, but we noted whether that group was a subset of a chief governing committee.) And lastly, we listed the gender split of office leaders, as well as practice and department leaders. We included coleaders, but not those who are second-in-command. Since it was not uncommon to have two partners coleading a practice (or one person overseeing multiple practices or offices), we calculated proportions based on total head count.

The results painted a picture where women were still very much the minority in firms’ top power structures. Only 14 firms had even one governing committee with female partners accounting for more than 25 percent of its members. Among the respondents, women occupied an average of 16.8 percent (1.8 seats) of the 10.8 seats on the smallest (or only) governing committee. Among the 37 firms with a second governing body, women partners occupied an average of 20 percent (5.0 seats out of 25.8 seats) on the larger governing committee.

The data for compensation committees, practice groups, and office heads wasn’t much better. On the firms’ compensation committees, women occupy an average of 2.3 out of 12.8 seats (18 percent). They represent 20 percent of practice group leaders and 15 percent of office managing partners. And often, these percentages reflect a degree of double-counting: It was not uncommon for the same one or two senior women to occupy seats on multiple high-powered committees.

No one is happy with these numbers. "Clearly law firms are not where we would like to be or should be when you look at the demographics of law school graduates and incoming asso­ciates," says Morgan Lewis chair Francis Milone, a point conceded by virtually all 28 law firm leaders and partners interviewed for this story.

But there certainly weren’t a shortage of explanations. The most-cited one: The higher rate of attrition among women lawyers makes any type of gender balance among leadership a virtual impossibility. With women constituting an average of only 15 percent of the equity partner ranks, it’s not a surprise that the leadership ranks should be similarly weighted toward men, say many law firm leaders. "Partners making election [decisions for leaders] will be dealing with the pool that they have; if that pool is limited, the results are [going to be] limited," says Milone.

Another explanation high on the list: the perceived low numbers of women rainmakers in the profession. "It’s almost a law of physics that lawyers won’t follow [or elect] someone who has not been a resounding success as a lawyer," says Orrick, Herrington & Sutcliffe CEO Ralph Baxter. "And when you look at the big rainmakers in U.S. law, there aren’t as many women," he says, noting that the client market still contains biases against women. That belief—which might be subject to biases itself—is echoed by many law firms and recent research. In the most recent report by the National Association of Women Lawyers (NAWL), almost half (46 percent) of all Am Law 200 firms report no women rainmakers among their top 10 business generators; another third report only one.

Some partners argue that management or executive committee memberships may be an unwanted prize in the midst of busy practices and 24-hour days. Many women partners, as well as men, would rather devote time to networking with clients or a life outside the office. "[These committees] are real work, and much of it is administrative and invisible," says one partner at an Am Law 50 firm who says she would rather not serve on her firm’s executive committee. "It’s not that I’m opting out; it’s that I’m making an intelligent choice with my time," she says. Even women who have populated the upper tiers of management express some ambivalence. "It’s certainly not the most productive time I have spent at the firm," says another female partner at an Am Law 50 firm about her tenure on the firm’s management committee.

And the all-around dismal gender numbers in leadership at The Am Law 100 make it easy to argue that the larger world—with its sociological pressures on women to balance home lives, and the residual biases against ambitious women—is more at fault than individual law firms—each of which can point to a slew of female-friendly policies such as part-time programs and business development seminars.

"As a mother with three daughters, it’s fair to say that I’m disappointed with where the world is, but I’m not disappointed in Davis Polk," says partner Nora Jordan, noting that during her 30-year career, she spent several years working part-time, served as chair of the firm’s compensation committee, and has been head of the firm’s investment management group for a decade. To Jordan, that history trumps the fact that Davis Polk has yet to have a female on its three-person executive committee.

Numbers, of course, don’t ever tell the whole story. There are firms, like Debevoise & Plimpton, with a group of powerful women practice leaders and rainmakers that today have only one woman on their eight-partner management committee. And there are others, like Gibson, Dunn & Crutcher, that might be penalized by timing: Gibson had four women on its 15-partner executive committee in 2011; today it has two.

But hard numbers can be revealing, and looking at the numbers, a handful of firms stood out. These firms have a combination of policies, practices, and even clients that have helped them achieve a better balance. One common thread among firms with higher ratios of women in leadership is the willingness to use appointive power and management edicts to drive diversity. Take the gains made by Fulbright & Jaworski during the 10-year tenure of chairman Steven Pfeiffer. The Houston-based firm’s governance enables the chairman to appoint the executive committee and heads of departments, and Pfeiffer didn’t hesitate to use that power to advance diversity goals.

"For me, it was a pretty obvious opportunity that needed to be seized," says Pfeiffer, "If you’re a woman, and it’s just a bunch of white guys directing the institution, how can you feel confident that at those critical moments, there would be a woman’s perspective in the room?" he says.

The upshot is women partners went from occupying one seat out of seven on the executive committee to three women out of six by 2007, a 50:50 gender ratio that continues today and is the highest gender ratio on a governing committee of all 93 respondents. Women partners also lead key offices such as Houston, New York, and London.

Similarly, Reed Smith today reports one of the highest percentages of women leaders, a fact that managing partner Greg Jordan largely attributes to the firm’s decision 12 years ago to consider diversity when nominating certain executive committee seats. In 2001 the firm amended its partnership agreement to provide for three "at-large" executive committee seats that would be nominated by the executive committee itself "to correct any imbalances" in representation. Previously, the nonmanagement members of the executive committee had been elected by partnership vote. "And we had a very white and male partnership and an [executive committee] that looked like that partnership," says Jordan. The "at-large" seats allowed the executive committee to directly adjust the gender, racial, and geographical diversity of the group, he says.

Over the next decade, the number of women who held seats on Reed Smith’s executive committee went from three (or 17 percent of a then-smaller 18-member committee) in 2001 to nine seats, or 38 percent of a 24-member committee in 2012, a proportion that well exceeds the percentage of the firm’s women equity partners (20.1 percent). Over time those appointments have created momentum for women partners in the open elections, says Jordan. Four of the six women currently holding voting seats on the executive committee, including newest committee member Julia Krebs-Markrich, obtained that seat in an open election, says Jordan. (Only 16 executive committee members hold voting seats.)

Getting younger partners involved in leadership positions is another way to ensure a degree of gender balance in leadership. "At many firms, management is very senior-based and top-down, and that [approach] tends to collect a lot of older white men," says Finnegan, Henderson, Farabow, Garrett & Dunner managing partner Barbara McCurdy. Her own resume is evidence of the firm’s tradition of giving younger partners a voice in management. As a third-year partner in 1996, McCurdy was appointed to a special 10th seat on the compensation committee to represent young partners. Almost 15 years later, McCurdy became managing partner as she was just turning 50, at the peak of her practice. "At some firms the managing partner is floating out toward retirement. The mentality here is letting the next generation lead the firm, and that naturally creates openings for women," she says.

Similarly, Kim Koopersmith, the newly minted chairperson-elect of Akin Gump Strauss Hauer & Feld, credits current chair R. Bruce McLean and his long-running focus on grooming younger partners as critical to her success as a leader. It was McLean, for instance, who gave Koopersmith some of her earliest leadership roles, including the drafting of the firmwide policy for part-time work arrangements in 2001. Six years ago, McLean informed Koopersmith that she was one of a handful of young partners that he thought could ultimately lead the firm. Over the next few years, McLean made sure that Koopersmith, as well as a few other candidates, got a variety of leadership experiences and exposure among the partners. For Koopersmith those experiences included chairing the compensation committee and her appointment as U.S. managing partner in 2008. In October the 53-year-old partner was elected as the first woman chair of the firm.

Not surprisingly, firms that have nurtured or attracted a large number of female rainmakers also boast a better balance in their leadership ranks. Some, such as Jenner & Block, have a long and storied history of women leaders. Former partner Joan Hall was elected to the firm’s executive committee in 1978 and was renowned for gathering women together over lunch in the seventies and eighties to talk about business development. Today, managing partner Susan Levy says there is a sizable group of women partners with "big numbers by their names," and women are the relationship partners for three of the firm’s top 10 clients. The Chicago-based firm has seven female partners on its 24-member management committee (29 percent) and two women on its eight-partner policy committee (24 percent).

But the ascendancy of female rainmakers need not take three decades. Take Shook. Over the last decade, the Kansas City, Missouri–based law firm has worked with clients such as Altria Group Inc., The Coca-Cola Company, E.I. du Pont de Nemours and Company, Microsoft Corporation, and Pfizer Inc. to create a diverse team of lawyers and to provide opportunities for women to lead and cultivate business, says Shook partner and executive committee member Lucy Mason.

Mason’s own relationship with Altria is a prime example. She began working for the tobacco company as a young associate under two more senior male partners. But in 1999, an in-house lawyer at Altria suggested that Mason was ready to act as second chair in the trial of an important personal injury case. And Mason, who was still an asso­ciate, shined, examining many of the trial’s key witnesses.

"That trial was a make-or-break moment for me: It really pushed me [forward] in the ranks," says Mason, who is now the primary relationship partner for Altria. "The client said out loud that they had confidence in me, and it was that push that gave me legitimacy," she says. That type of client influence and support has had a significant impact on the gender balance of Shook’s leadership, says Mason. Today, four women serve on the firm’s 11-partner executive committee (36 percent), and women make up 32 percent of the firm’s division and practice group leaders and 22 percent of its office managing partners. "The clients drive the business," she says. They’ve been demanding more women in leadership positions, and we’ve responded to that."