Effective writing is an essential skill for all doctoral students, yet it is one that receives relatively little attention in training and supervision. This article explores extensive feedback from participants in a series of workshops for doctoral candidates engaged with writing up qualitative data. The themes arising from the data analysis are discussed in terms of the affective domain of writing, and the main claim is that writing up qualitative data has been identified as what Meyer and Land would call a threshold concept for doctoral candidates employing qualitative analysis. Drawing on Turner's notion of liminality, the article concludes that interdisciplinary workshops can be instrumental in helping doctoral candidates understand the role of writing, and of writing up qualitative data in particular, in their development into independent, autonomous researchers. (Contains 3 notes.)