Welcome to the 12th edition of the Vault Guide to the Top 100 Law Firms, the most comprehensive, candid, up-to-date guide to the most prestigious law firms.

This year, our guide has a new look and format, with profiles of more law firms than ever before. We offer a ranking of 100 of the nation’s top firms, complete with 100 law firm profiles incorporating quotes and opinions from thousands of associates. The guide also provides a glimpse of more than 60 additional firms, with contact and salary information, office locations, notable perks, major practice areas and more, including the ever-popular “Buzz” section, in which associates offer observations about firms other than their own.

Vault’s associate survey continues to attract more and more respondents, who make our rankings more comprehensive and add depth to our profiles. In 2009, more than 15,000 associates at more than 150 of the most prestigious firms in the country took our survey, ranking their peer law firms based on overall, regional and practice area prestige. (Associates were asked to only rank those firms with which they were familiar.) We took those scores and calculated the Vault Top 100.

We also asked associates to comment on and rank their own firm in terms of general satisfaction, hours, compensation, diversity, treatment by partners, selectivity in hiring, and other factors. From this data, we calculate an array of “Quality of Life” rankings, including our “20 Best Firms to Work For.”