Great Lakes iron ore producers had faced no competition from foreign iron ore in the Great Lakes steel market for nearly a century as the 1970s closed. In the early 1980s, as a result of unprecedented developments in the world steel market, Brazilian producers were offering to deliver iron ore to Chicago (the heart of the Great Lakes market) at prices substantially below local iron ore prices. The U.S. and Canadian iron ore industries faced a major crisis that cast doubt on their future. In response to the crisis, these industries dramatically increased productivity. Labor productivity doubled in a few years (whereas it had changed little in the preceding decade). Materials productivity increased by more than half. Capital productivity increased as well. I show that most of the productivity gains were due to changes in work practices. Work practice changes reduced overstaffing and hence increased labor productivity. Changes in work practices, by increasing the fraction of time equipment was in operating mode, also significantly increased materials and capital productivity.