Among low- and middle-income countries, there is evidence that populations experiencing rapid political and economic transition have particularly high burdens of disease and disability from mental health conditions. This paper undertakes a political economy analysis of mental health in Vietnam to enhance knowledge translation, notably how both explicit and tacit knowledge can be used to promote evidence-based policy making. It argues that Vietnam's experience illustrates the need to better understand, not only how transition transforms societies, but how it impacts on the mental health needs and care of populations. The political economy of transition in Vietnam has so far given highest priority to economic growth through integration with the world economy and public sector reform. There is a need to recognise that transition in Vietnam poses both a potential threat to the care of people with mental health needs, and an opportunity to develop mental health services appropriate to local contexts.