Fifty years ago, McMaster University's Faculty of Medicine (as it was known at the time) embarked willy-nilly on a pedagogical experiment that, unbeknownst to its conceivers, would reverberate through higher education across the globe in the ensuing decades. The characteristics of that experiment have been described at length elsewhere (Servant-Miklos 2019a; Spaulding 1991), but what is most remarkable about it is the extent to which it shaped medical education research, and then spilled into all areas of higher education, from engineering to liberal arts, and from Brazil to China. Commemorating the 50 th anniversary of problem-based learning goes beyond just acknowledging the contribution of the pioneers of PBL to medical education (though this definitely can and has been done). It really plugs us into key current debates about pedagogy and education research in and beyond the health sciences education sphere.Let's start with the recognition that PBL did indeed radically transform medical education over the past 50 years. Of course, not every medical school in the world uses PBL today, and even among those that do, the quality and quantity of implementation varies greatly. But the diffusion of PBL in medical schools around the world changed the discourse around medical education, challenging old notions of the division between basic sciences and clinical skills, and questioning traditional, top-down forms of contents delivery. This is especially true in schools located near deprived communities in the Global South where PBL was interpreted as an opportunity for engaging students in community outreach from the earliest years of their medical education. Outside of medical education, the spread and implementation of PBL has been haphazard, but nonetheless enthusiastic. All manner of creative interpretations have emerged, quite often in a grassroots manner, at the behest of inspired teachers looking to do things differently, in some cases with greater success than others. What this has created is a vibrant community of educators and scholars around