Published Article / The role of the Projection Principle within Chomsky's Government-Binding (GB) Theory is to preserve the subcategorisation properties of lexical items at all levels of syntactic representation, viz. D-structure, S-structure, and Lexical Form. Arguments have been made that the Projection Principle is a new concept that is simply an extension of theTransformational Component (XFM) and Emonds' Structure-Preserving Constraint (SPC), and that it does not deserve the high status it has been accorded in GB theory. This paper provides evidence, based on sentences involving movement operations, that the Projection Principle is innovative and that it convincingly addresses what theXFMandSPChave failed to address.