Is there a principled difference between entailments in natural language that are valid solely in virtue of their form or structure and those that are not? This paper advances an affirmative answer to this question, one that takes as its starting point Gareth Evans’s suggestion that semantic theory aims to carve reality at the joints by uncovering the semantic natural kinds of the language. I sketch an Evans-inspired account of semantic kinds and show how it supports a principled account of (...) structural entailment. I illustrate the account by application to a case study involving the entailment properties of adverbs; this involves developing a novel proposal about the semantics for adverbs like ‘quickly’ and ‘slowly’. In the course of the discussion I explore some implications of the account for the place of model-theoretic tools in natural language semantics. (shrink)