This squib presents a restriction on the phenomenon descriptively known as ‘‘vehicle change’’ that has not, to our knowledge, previously been noted. With vehicle change construed as a kind of ‘‘tolerable mismatch’’ between an ellipsis site and its antecedent, the data we present suggest that exactly the same mismatches cannot be tolerated between the members of a movement chain. While in principle one might consider the possibility that ellipsis and movement could be reduced to the same operation ( Chomsky 1995:252–253 )—that the deletion usually described as ellipsis might be the same operation as the deletion or ‘‘chopping’’ (in the sense of Ross 1967) that applies to the unpronounced (usually lower) copy in a movement chain—the differences in the kinds of mismatches that can be tolerated will pose a difficulty for this unification. We present the crucial data that suggest that such a unification is not tenable in section 1 and then outline an explanation of these facts in section 2 . We state this explanation in terms of the way movement, ellipsis, and vehicle change interact, while remaining largely agnostic about the exact mechanisms that implement these somewhat pretheoretic notions. In section 3 , we consider the consequences for these more fine-grained questions about the nature of ellipsis and movement, and in section 4 , we consider some further implications that depend on how vehicle change is understood. Section 5 addresses a challenge for our proposed explanation that turns out to be only illusory, and section 6 briefly concludes.

We propose an account of adjunct extraposition that does not invoke rightward movement. Instead, the noncanonical placement of adjuncts at the right edge of a sentence arises from the very same mechanisms that allow adjuncts to behave flexibly with respect to basic constituency tests and to avoid reconstruction. The system we propose naturally explains the locality restrictions on extraposition and certain interactions between extraposition and movement, and dovetails with an analysis of how adjuncts semantically compose with their hosts.