From the text: ‘Risk’ is an established domain of research in various academic disciplines (e.g., mathematics, statistics, probability, economics, engineering, political science, business, earth science, health science, computer science, psychology, sociology, and law). At present, risk, as a domain of research, is not similarly established in the field of mathematics education. However, there is established research on risk from members of the mathematics education community. Further, the established research on risk from the fields of psychology and the popularization of mathematics and statistics is consistently found in the relevant mathematics education research literature. As such, one could argue that risk, as a domain of research in the field of mathematics education, is starting to take shape. This special issue aspires not only to further investigate established research threads pertaining to risk, but, also, to identify and investigate, that is, extend the purview of risk research in the field of mathematics education and beyond. To achieve this lofty goal, over 40 individuals from various academic disciplines (e.g., mathematics, statistics, psychology, popularization, education and cognitive science ) have contributed 26 articles, which, collectively, comprise the broad-based, interdisciplinary special issue on risk, mathematical or otherwise, that I had hoped to achieve when I was invited to guest edit this special issue. I wish to thank those individuals, here, for helping my plan come to fruition.