The zone of proximal development (ZPD) is a well-known and frequently used notion in both educational research and practice with a wide and diverse range of interpretations. My aim in writing this theoretical article is not to provide a critical examination or an extensive literature review of the ZPD, but rather to highlight some significant issues surrounding the use of the notion in the mathematics education literature. Extending a series of questions contributed by Del Río and Álvarez, I have added an element about theoretical space enabling researchers who are not in psychology to use the questions to situate their own use of the ZPD within their theoretical perspective and to unpack their assumptions about each of the questions. More importantly, the paper exemplifies how the use of an organising framework assists in achieving some clarity on the different ways the notion is conceptualised in the educational literature. I propose that this framework could enable both researchers and educators to locate their own conceptualisation of the ZPD within the broader, complex space and to assist in achieving coherence between the theoretical and methodological perspectives they work with.