Over the past few years the concept of a ‘STEM curriculum’ has been promoted across many nations. Policies from countries such as the USA, UK and Australia place a priority on improving the performance of both school students and teachers to graduate with Science, Technology, Engineering and Mathematics (STEM) qualifications. Economic and educational drivers are identified to justify this policy setting. But there is ambiguity about how a ‘STEM education’ should be implemented. School students’ performances in STEM subjects tend to be reported by individual subject or discipline rather than as an integrated suite of subjects. Some argue that STEM is simply the aggregate of each individual subject, while others posit that STEM is more than the individual component subjects, and instead refers to an integration of the respective subjects into a new ‘whole’. But there does not appear to be a national or international consensus about what is STEM, nor what theoretical or conceptual framework should inform a ‘STEM education’. As such, this paper explores the literature that outlines different models of understanding a STEM education to argue that STEM has to be more than an aggregation of individual subjects, and instead should be conceptualized as an integrated curriculum accompanied by pedagogies appropriate to the nature of the curriculum.