This thesis sets out to explore the complexity of curriculum reform by examining how different stakeholders, experiencing English language curriculum reform in different ‘layers’ of the education system in one province in Vietnam, make sense of change in relation to their professional roles, practices and behaviours. While there is a plethora of research on curriculum change in TESOL contexts, much of this is focused on the teacher and the practical constraints they might face in implementing a new curriculum. The multi-level interactions and relationships involved in sense-making, and the complexity that such interconnectedness suggests, seems to be a neglected research area. This qualitative case study begins to fill this research gap. Using a complexity perspective, the study investigated the perceptions, understandings and responses to primary English language curriculum change of seven primary English language teachers working in three districts in one province in Vietnam. The study also examined the sense-making of three district specialists and four university INSET trainers who are involved in supporting those teachers in implementing the new curriculum. Data were generated through multiple qualitative interviews, classroom observations and document analysis carried out over two research phases. The research identified a number of control parameters which appeared to be constraining the participants’ practices and behaviours towards a paradigm shuffle rather than a paradigm shift. The findings show how the interconnectedness of the educational culture, perceptions of risk, feelings of being supported and the flow of communication experienced by the different participants seemed to mediate teachers’ emergent classroom practices and behaviours. The research identifies several policy implications for policy makers, curriculum change planners and TESOL practitioners which have emerged from these control parameters, and which are likely to help promote the desired curriculum change outcomes.