Aspiring middle school teachers in the United States take fewer math courses and are less knowledgeable in the subject than their counterparts in South Korea, Taiwan, and other countries. That gap in teacher preparation, coupled with curricular differences, could help explain achievement disparities between American students and their peers in other industrialized nations, researchers say. The preparation of teachers to impart high-level mathematics skills at the middle and high school levels has been gaining attention as U.S. business leaders and policymakers express worries about the ability of schools to train a globally competitive workforce. Now, in a study released this week, researchers are offering data on teacher education that hint at the extent of the problem. This article reports on the study of those on the brink of becoming middle school teachers in the U.S. and five other countries--Bulgaria, Germany, Mexico, South Korea, and Taiwan--which concludes that American teachers are ill prepared for the task.