In the twenty years since Ray Land and Erik Meyer published their first paper on Threshold Concepts, there has been a steady stream of papers mulling over their original suggestions that learning, far from proceeding in an orderly fashion, is instead a process of struggle – perhaps alienation and confusion – that puts students in a troublesome liminal ‘in-between’ state. As their understanding develops, liminality gives way to transformational insight whereby a whole field of study comes, often quite abruptly, into focus. There is a gain but often also a loss: in this new world, old certainties, assumptions and even aspects of our identity can be left by the wayside. Threshold Concepts in the Moment is the sixth collection in the series on the subject of Threshold Concepts, following the 8th Biennial Conference held in 2021, anchored at London’s UCL but running online across the world. Its contributors, who range from ‘old hands’ to new members of the community finding their feet, mull over the insights of the threshold concepts framework in higher education, scrutinise their own fields of study, explore the implications of liminality for pedagogy and becoming professional practitioners, and consider the broad implications for pedagogy of factoring in the troublesomeness of knowledge and learning.