Much of the research on the effects of tests on foreign and second-language classrooms has examined the impact or washback effect that commercial/institutional language tests, such as the TOEFL, have on teachers' instructional practices (Hughes, 1998; Wall & Alderson, 1993). Using a case study methodology, this study uncovered the ways in which the classroom practices of one teacher and his students interact with their perceptions of the validity of the TOEFL-specifically, the extent to which they view the TOEFL as an accurate measure of English language proficiency. The findings indicate that a great deal of tension and ambiguity surround the TOEFL's status as an accurate measure of English language proficiency. Both the instructor and his students described the TOEFL as "full of tricks" and believed that the variety of English tested was not the variety of English used in day-to-day interactions with native speakers of English. However, the teacher allowed the institutional authority of the TOEFL to trump his native speaker intuitions and when students' TOEFL scores did not match their actual classroom performance, he allowed the TOEFL to trump his judgments about their English language proficiency. The conclusions suggest that TESL/TEFL programs adopt a more critical view of high-stakes tests and the ways these critical views might clash with institutional policies so that ESL teachers are better prepared to encounter such tensions in their careers.