Abstract The teaching of Phonetics and Phonology in multilingual classrooms now-a-days is fraught with multifaceted challenges. These are caused by students’ abhorrence for the course, their displeasures at the compulsory status assigned to it, students’ attitudes towards it, lack of basic and functional laboratory facilities and other social and psychological factors affecting learners who constitute the major classroom participants. This study investigates the teething problems encountered by teachers who teach Phonetics and Phonology in tertiary institutions; it uses a private university in Ogun State, Nigeria as a case study. The population of the study comprises all students from the Departments of Languages and Mass Communication of the University in question. The study adopts a descriptive research design and an ex post facto design; it equally uses Contrastive Linguistic Analysis (CLA) and Articulatory Phonology (AP) as theoretical frameworks. Also, Participant Observation Method and Focus Group Interviews were used as instruments for data collection. Simple random technique was adopted in selecting both the target population (of 35 students from 200 level and 300 level) and the data (3 lectures) for this study. One of the major findings was that the interference of students’ Mother Tongue (MT) in the pronunciation of English sounds (especially those that were not in existence in their MT) was prominent in the practical classes; and this frustrated teacher’s effort in teaching the course. The researcher therefore recommends that educational stakeholders (especially the government at all levels) should provide basic laboratory facilities, motivation and training for teachers who go extra miles to teach students Phonetics and Phonology; and ensure that they understand and practice it.