Large U.S. law firms became less diverse last year. That’s the key finding to emerge from the latest version of our annual Diversity Scorecard, which counts attorneys of color in the U.S. offices of some 200 big firms. In each of the previous nine years that we’ve compiled the Scorecard, the percentage of minority attorneys at all participating firms increased, rising from less than 10 percent in 2000 to 13.9 percent in 2008. In 2009, for the first time, that proportion dipped, to 13.4 percent.

The drop in law firm diversity may be small, but it’s important. Overall, big firms shed 6 percent of their attorneys between 2008 and 2009–and, amid the bloodletting, lost 9 percent of their minority lawyers. (Here and elsewhere in this story, we’ve calculated such percentages only for the 191 firms that provided numbers in both years, in order to have a consistent basis for comparison.) Diversity advocates call the drop a warning sign that shouldn’t be ignored. “I think [that] when you’re looking at any numbers of a population you’re trying to increase, and you see a decrease, that’s significant,” says Venu Gupta, executive director of the Chicago Committee on Minorities in Large Law Firms. “I guess I hoped we wouldn’t be going backward,” echoes Fred Alvarez, chair of the American Bar Association Commission on Racial and Ethnic Diversity in the Profession and a Wilson Sonsini Goodrich & Rosati partner.