The country’s largest labor and employment firms enjoyed strong growth in 2018, thanks to high demand that has been spurred by litigation, new laws and regulations, multinational clients and the #MeToo era.

But each of the four top-grossing U.S. firms—Littler Mendelson; Ogletree, Deakins, Nash, Smoak & Stewart; Jackson Lewis; and Fisher & Phillips—has relied on its own model for growth, ranging from differences in partnership structure and international strategy to the firms’ specific practice priorities and investments in technology.

Revenue and Head Count Gains