Given the primary role of teachers in affecting student achievement, U.S. policy makers and reformers have increasingly focused on monitoring and evaluating teacher effectiveness by emphasizing the links to student learning outcomes. Large-scale international assessments are frequently used as base examples to justify reform. But, relatively little is known about what other countries actually do. The authors wonder: How do other countries evaluate teachers? They have set out on a broad research effort, looking at whether top-performing countries use educational practices and reform initiatives in vogue in the U.S. They have compared Finland, Korea, Japan, Ontario in Canada, and Singapore, exploring in each system the role of high-stakes testing, policies used to motivate schools and teachers to improve student learning, and the organization of accountability for learning. They use Ontario because Canadian education policy is substantially decentralized to the provinces. In each area, they looked at the role of teachers and systems of teacher evaluation. Perhaps not surprisingly, they have learned: (1) Teacher evaluation is used for both accountability and instructional improvement in most school systems; however, teacher evaluation systems are organized differently depending on the model of accountability; (2) There is a growing trend to use student test results and metrics to inform accountability for schools, principals, and teachers, instructional improvement in classrooms and schools, and reform at the system level; and (3) In particular, standardized testing of students, a primary and growing component of teacher evaluation in the U.S., is generally administered and used differently in other countries. How is teacher evaluation linked with accountability and instructional improvement? Looking across systems, the authors see four primary approaches to accountability: professional, organizational, market, and parental/community. In this article, the authors discuss each approach that has strong implications for teacher evaluation and its use in instructional improvement. (Contains 1 figure.)