Over the past few decades, research has demonstrated the important role that prosody (i.e., stress, rhythm, intonation) plays in the intelligibility of speakers of English as a second language (ESL). Yet the impact of this research on teacher cognition--the beliefs and knowledge that teachers possess in relation to their classroom practices--has received limited attention. This article explores how research into English prosody has influenced pronunciation instruction in the ESL classroom, teachers' knowledge and beliefs about this instruction, and what teachers believe to be the most effective way to improve their knowledge base in this area. In particular, the opinions of teachers of beginning, intermediate, and advanced classes are investigated. Through semistructured interviews with five instructors and the pronunciation journal of the author, these issues are examined. Results show that research into English pronunciation has clearly influenced the teaching and prioritization of features of pronunciation for instructors with graduate education that has included a course dedicated to pronunciation or pronunciation pedagogy. However, even with this education, teachers may lack confidence in teaching different aspects of pronunciation. (Contains 3 tables.)