The fourth annual Washington DC Industrial Organization Conference was held at 1400 16th Street NW in downtown DC on Friday, May 12, 2017. The program committee (Emek Basker (Census), Nate Miller (Georgetown), and Daniel Vincent (UMD)) selected a program that highlighted a range of theoretical and empirical topics in industrial organization. For the first time, the conference also included a poster session at which selected advanced graduate students at local universities presented their dissertation research.