Abstract:Mathematics education, as a field of study, comprises numerous and diverse research traditions including those of philosophy, sociology, psychology, history, and, of course, mathematics. The nature of mathematics educational research, as a result, is therefore complex. What questions are asked and what constitutes “fact” are aspects of this research. To study the appropriateness of questions and fact, Uprichard (1982) proposed a hierarchy of levels of educational research ranging from theory construction to validation. In this editorial and commentary, his levels in the context of current research initiatives such as action research are revisited, with a view to determining characteristics required for appropriate matches between research methods and the nature of research questions posed.