This study aims to better understand Vietnamese learners' views of potential learning problems and the impact of teacher-related factors on English pronunciation learning. It examines how more successful and less successful learners perceive pronunciation instruction and the problems they face when learning the L2 phonological system. In this mixed-methods study, 48 first-year English major students (26 strong and 22 weak) at a Vietnamese university were first polled about their learning difficulties and their perceptions of the pronunciation instruction available to them. Four strong and four weak students (chosen using both human raters and a computer-aided rating scheme) then partook in semi-structured interviews. The findings reveal that both groups differ in terms of the difficulties they face, their learning goals and language models, and their assessment of the teaching content and techniques. Several important implications were made regarding the learning goals, the status of non-native teachers, and the discrepancy between learner perception and teacher cognition of pronunciation instruction.