Across the educational systems of the world, few issues receive more attention than the problem of ensuring that elementary- and secondary-school classrooms are staffed with adequately qualified teachers. Even in nations where students routinely score high on international exams, the issue of teacher quality is the subject of concern. It is widely believed that the quality of teachers and teaching are among the most important factors shaping the learning and growth of students, an impact that goes beyond student academic achievement. Across the world, observers routinely tie the performance of teachers to numerous, larger societal goals and problems, including economic competitiveness and productivity, juvenile delinquency, and moral and civic culture. Along with a general consensus among many nations that the quality of teachers and teaching is a vital resource, there is accordingly concern surrounding how equitably this resource is distributed within educational systems. Some nations suffer from an apparent paradox: despite an overall overproduction and oversupply of new teachers, there appear to be substantial numbers of students without access to qualified teachers. This report presents the results from a collaborative, comparative study of the qualifications of elementary and secondary teachers undertaken by a group of scholars, policy makers and senior education officials from six nations and one region: United States, Korea, China, Hong Kong, Singapore, Thailand, and Japan. This study revealed both commonalities and differences in the preparation and qualifications of teachers among the seven systems examined. Comparative educational research can provide a useful function by placing educational systems in context. Results from each nation or region are individually presented. The study suggests at least three possible sources of the problem of under-qualified teachers: (1) Pre-employment requirements and standards; (2) Failure of the teaching force to meet existing requirements and standards; and (3) How teachers are utilized once on the job due to mis-assignment or out-of-field teaching. Focusing on upgrading the training requirements of teachers and teacher recruitment may overlook the impact of the organizational and occupational contexts within which teachers work. The data indicate that solutions to the problem of under-qualified teachers also must look to how schools are managed and how teachers are utilized once they are on the job. Recruiting thousands of new candidates and providing them with rigorous preparation will not solve the problem if large numbers of teachers receive assignments for which they are not prepared. (Individual chapters contain tables, figures, and references.) [This report by Richard M. Ingersoll was written with Ding Gang, Sun Meilu, Kwok Chan Lai, Hidenori Fujita, Ee-gyeong Kim, Steven K. S. Tan, Angela F. L. Wong, Pruet Siribanpitak, and Siriporn Boonyananta. For related policy brief, see ED498346.]