In recent years, second language (L2) pronunciation instruction has become a focus of considerable research, conducted in contexts on a continuum ranging from pure laboratory settings to intact classrooms. One notable outcome of a majority of these studies is a change in L2 speakers’ pronunciation as a result of instruction. However, the value to the students is not entirely clear in many instances. Ideally, pronunciation instruction should result in better perception of L2 phonology on the part of the learners, as well as oral productions that are more intelligible and comprehensible to interlocutors. Perception has often been unmeasured in pedagogical studies, and production, in the majority of instances, has been measured in terms of accent reduction, rather than improved intelligibility and comprehensibility. Since it is possible to modify accent without changing how understandable a learner’s speech is, accent-focused studies do not necessarily contribute as much as they claim to the overall value of pronunciation instruction. The benefits of enhanced intelligibility and comprehensibility are clear: increased communicative effectiveness (the message) and increased willingness to communicate on the part of the speaker and the interlocutor (affective or social considerations) are desirable results. In this chapter, the existing research on the efficacy of L2 pronunciation instruction will be summarized and the current state of the field will be described. Second language teachers’ ongoing reluctance to engage in pronunciation instruction will be explored, as will be the complexities facing instructors in the classroom. Intelligibility, comprehensibility, fluency and social issues will be addressed. Finally, suggestions for further research will be made, especially research that engages the learners and interlocutors well after the instruction has taken place.