Projection, as understood here, is (roughly) the phenomenon whereby some element of sentence content "survives" embedding under an entailment-canceling operator such as negation. For example, an utterance of the sentence Jane hasn't finished her homework typically conveys that Jane has homework, even though the expression which gives rise to this implication is embedded under negation.

In the course of the last 40 years or more, projection has been studied in the context of presupposition, and indeed has often been taken as a defining feature of presuppositions. More recently, it has been observed by a variety of authors that elements of content which are not otherwise presupposition-like may project. The contents of non-restrictive relative clauses and other appositives are central cases.

In this paper, we develop the idea that projection is a property, not specifically of presuppositions, but of what we call not at-issue content. Roughly, content which is at-issue is content which serves to address the current Question Under Discussion (Roberts 1996); all other content is not-at-issue. In this paper, we will elaborate on the notion of at-issueness, motivate the claim that at-issueness is the central explanatory notion in an account of projection, and provide a preliminary model of some cases of projection.