Anyone who has tried to learn a language with a very different sound system will understand the challenges faced by speakers of a language as different as Vietnamese who are attempting to learn to speak English in a way that is intelligible to non-speakers of Vietnamese. Many learners have very limited opportunity to hear model pronunciations other than their teacher's, and no opportunity at all to speak in English outside the classroom. Vietnamese-accented English is characterised by a number of features which ride roughshod over English morphosyntax, resulting in speech that is extremely difficult to reconstruct for the non-Vietnamese-speaking listener. Some of these features appear to be more difficult to learn to avoid than others. Phonotactic constraints in L1 appear to be persistent even in L2, and L1 phonological rules will, apparently, often apply in L2 unless they are blocked in some way. Perception of salient (to native listeners) target pronunciations is often lacking, and learners may not be aware that their pronunciation is not intelligible. Despite years of language study, many learners are unable to produce some native speaker targets. Vietnamese learners typically exhibit a set of characteristic pronunciation features in English, and the aim of this study is to see which of these are susceptible to remediation through explicit teaching. This explicit teaching is compared with a less direct, less interactive kind of teaching, involving drawing native and native-like pronunciation of problematic features of English pronunciation to the learners' attention. The results of this study can then be interpreted in terms of teachability and learnability, which do not always go hand in hand. If we understand what kinds of phonetic features are teachable and how learnability varies for different features, we can target those features where there is a good return for effort spent, resulting in efficient teaching.