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 chart shows, it was a tale of ones and twos among many of the chief governing committees [see "A Complicated Census"]. 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.”