Methodology: The NLJ 500 is the National Law Journal's survey of the 500 largest law firms in the United States covering the previous calendar year. Data is collected from firms at the same time as the Am Law financial numbers. ALM sent surveys this year to more than 900 law firms to determine the 500 largest U.S.-centric firms by headcount. Firms smaller than No. 350 are divided into two tiers instead of earning individual ranks.

Lawyer totals are based on the average number of full-time equivalent (FTE) attorneys for the period between Jan. 1 and Dec. 31, 2019. For firms that did not participate in the survey, ALM research estimates lawyer counts based on information that is available on firm websites and collected in ALM's Legal Compass database as of Dec. 31, 2019. Those numbers are reduced by 5% to estimate average FTE lawyers for the calendar year.

In the case of a tie of total lawyers, firms are ranked by their total number of partners, and ties at that level are broken by total number of equity partners. Equity partners are defined as lawyers who earn more than half their compensation from firm profits rather than from salaries. "Other" lawyers are non-partner and non-associate-track attorneys, such as of counsel. Temporary and contract attorneys as well as non-lawyer billing professionals and staff at firms are not included in these head counts. A firm must have more lawyers based in the U.S. than in any other single country to be included on this list.