Developments in the field of gender theory as applied to education since the 1970s are briefly reviewed in order to highlight key challenges and debates around gender categorisation and identification in gender and education. We argue that conundrums of categorisation have haunted, and continue to haunt, the field of gender theory, and empirical applications (such as the case of education) in particular. We explain how we have attempted to address some of the conundrums arising in our own theoretical work, and analyse remaining challenges that we feel the field of education needs to address in order to advance theoretically. Identifying two key tensions underpinning this empirical dilemma of gender categorisation--the tension between agency and determinism in gender identification, and that between gender deconstruction and gender analysis--we seek to weave a path through some of these complex debates, and to indicate ways in which they may be addressed in future work. We argue that in order to avoid essentialism and reification of gender distinction, we need to apply a "three-fold" analysis that incorporates three different elements in our categorisation of gender: spectator perspective; respondent perspective and social context.