The document summarizes the findings of the 2015 Social Law Firm Index study, which ranked the top 100 U.S. law firms based on their use of social media. Some key findings include: 1) Large law firms have substantially increased their social media efforts and resources over the past year; 2) American law firms still lagged behind U.K. firms in social media usage; and 3) Marketing remains the top purpose for social media use among large law firms, though recruiting and client support have grown in importance.