This paper describes a newly collected, detailed database on national governments' use of the antidumping trade policy instrument. The data collection project was funded by the Development Research Group of the World Bank and Brandeis University. While still preliminary, it goes beyond existing, publicly-used sets of antidumping data in a number of fundamental ways. It is a first attempt to use original source national government documentation to organize information on products, firms, the investigative procedure and outcomes of the historical use (since the 1980s) of the antidumping policy instrument across large importing country users. The paper also reports more and recent data on a number of smaller users of antidumping, as well as some limited information on the use of countervailing measures from national governments that are users of countervailing duty laws.