Contemporary grammars such as Biber et al. and Quirk et al. acknowledge the class of complex subordinators such as as far as, in case, in order (that). However, there is no consensus on membership of this class, and temporal adverbial expressions such as (at) the moment (that) can be seen as borderline cases. This paper will argue that the emergence of the fully elliptical form-the moment-with zero preposition and zero that in an ambiguous context allows the reanalysis of an adverbial adjunct introducing a relative clause as a subordinator. Corpus data from the Australian, British and US ICE corpora are used to demonstrate which of a set of these temporal adverbials are most likely to be emerging in this subordinator role. The frequency and range of different types of subordinator in the spoken corpora are compared with written genres such as fiction where narrative (and therefore temporal subordination) is a feature. These findings are tested against similar genres in the larger BNC (British English) and COCA (American English) corpora. Written English, and fiction in particular, was found to be more productive of these new subordinators than spoken English.