It is difficult to perform speech acts for request, apology, complaint, compliment, greeting, or refusal in English as they can convey wrong information. Performing the speech act of refusal can be even more difficult for ESL or EFL students because refusal indicates one’s objection to the others’ offer, invitation, suggestion, or request. Particularly Korean students are easy to fail in expressing refusal politely in English due to many differences between Koreans and Americans: social and cultural differences and differences in performing the speech act and using semantic formulas. Their refusal thus often sounds pragmatically inappropriate even though it is grammatically perfect. In this paper, first, what kinds of differences are found between Koreans and Americans when refusing, what makes them misunderstand each other, and how instruction can help Korean students in it are discussed. And then five commonly used textbooks are reviewed to show how American refusal is taught, what kinds of problems are found, and what can be modified to teach it more explicitly and effectively. Finally, a sample lesson plan of teaching American refusal to Korean university students is presented to raise their pragmatic awareness as well as to enhance their pragmatic competence.