This article arises from a systematic review of the International Baccalaureate (IB) Primary Years Programme (PYP). Four databases were consulted, and after the application of inclusion and exclusion criteria, 21 articles were selected and analysed in the following categories: year and author, country, type of research, participants, purpose and results. The results show a growth in PYP research in recent years, coming from several countries around the world, using mainly qualitative or mixed methodologies with small samples of teachers, students, administrators and families in IB schools. There is great variety in the purposes of the studies, the most representative being comparative analysis of the implementation of the programme, the use of a language for IB teaching other than that of the country in which the school is located, and the treatment of interculturality. These studies find differences in the ease of implementation of the programme depending on the context and geographical location of the schools, and also highlight the benefits of the programme for intercultural education and foreign language learning. Some tensions can be observed between the PYP curriculum and national policies, and also in the training and predisposition of teachers towards this particular methodology. More research is needed on the academic benefits of the PYP in comparison with other methodologies that are also working well at the curriculum level.