The fullest account of English imperative sentences considered in the context of a transformational grammar is contained in Katz & Postal (1964: 74–9). Their account forms part of a discussion of the general thesis that transformations do not affect the meaning of sentences, and of the proposal that follows as a natural corollary of this thesis, that the set of optional singulary transformations be restricted to those usually referred to as ‘stylistic’ transformations. Instead of treating imperative sentences as derived from declarative kernels, therefore, they postulate the occurrence of an imperative morpheme (Imp) in the underlying phrase-markers of imperative sentences. This, they assume, marks these structures as the domain of the imperative transformations and imposes certain selectional restrictions upon them. The notion of the Imp morpheme, which is the most original and most important part of Katz and Postal's analysis of imperative sentences, is adopted in this paper and the occurrence of the morpheme in the deep-structure of all imperative sentences is assumed throughout it. In the rest of their analysis, however, Katz and Postal draw upon more traditional ideas, one of which is disputable.