Welcome to the inaugural NLJ 500. This year, we introduce the biggest-ever expansion of our annual NLJ 350 report—launched in 1978 with a ranking of 200 firms—to provide a more robust portrait of Big Law in the U.S. The additional 150 midsized law firms on the list bear watching as some grow into the large firms of the future, whether organically or through mergers with larger entities.

For the largest 350 firms on our list, head count numbers of attorneys in 2015 dipped slightly from the previous year, to about 146,600 lawyers, from 147,500 in 2014. That deflation flipped the 0.6 percent growth that took place in 2014. The overall numbers skew lower this year, in part because to the world’s largest law firm, Dentons, is no longer on the NLJ list. We explain why, and the impact of its absence, inside.