Agricultural commodity ‘dumping’ is the practice of exporting commodities at prices below the cost of production. Dumping cheats farmers of a fair return for their work. It cheats both the farmers in the USA who are paid below cost, and the farmers abroad whose crops compete with US exports in markets distorted by dumping. And dumping shortchanges the ecosystems upon which humanity depends for its survival. Neo-classical economics holds that when prices are low, suppliers will produce less. The persistence of dumping in the US agricultural commodity sector defies that assumption. In trade circles, where the problem is acknowledged to an extent, dumping is explained as a result of government subsidies. The authors argue that the dumping numbers provided by the Institute for Agriculture and Trade Policy suggest this explanation is at best partial. They look at definitions of dumping, and explanations for how it arises and why it persists, in defiance of expectations that markets are self-correcting.