<p>Sentence meanings and propositions are intimate, but don’t exactly get on. Two familiar divergences are (i) the diversity of linguistic forms (within and between languages) that intuitively ‘say’ the same thing, such as active/passive pairs, and (ii) the contextual determination of propositional content that the type linguistic form leaves undetermined. The paper doesn’t raise doubts about these phenomena, but offers a general framework under which sentence meaning is best theorised as mere constraints upon what can be said with a given sentence, where propositions themselves, as <i>what</i> can be said, are artefacts that do not require any theorising beyond an understanding of the states, linguistic or otherwise, they are employed to track for our descriptive and explanatory purposes. Two principal considerations will be presented in favour this general picture: semantic underdetermination and, more especially, polysemy/copredication. The former is not the familiar contextual underdetermination, but the more significant condition that linguistic material alone essentially leaves propositions underdetermined, whatever the context. The latter is where a lexical item can express, selectively or simultaneously, distinct extensions relative to distinct predicates.</p>