In this thesis, I focus on scalar implicatures, presuppositions and their connections. In chapter 2, I propose a scalar implicature-based account of neg-raising inferences, standardly analyzed as a presuppositional phenomenon (Gajewski 2005, 2007). I show that an approach based on scalar implicatures can straightforwardly account for the differences and similarities between neg-raising predicates and presuppositional triggers. In chapters 3 and 4, I extend this account to “soft” presuppositions, a class of presuppositions that are easily suspendable (Abusch 2002, 2010). I show how such account can explain the differences and similarities between this class of presuppositions and other presuppositions on the one hand, and scalar implicatures on the other. Furthermore, I discuss various consequences that it has with respect to the behavior of soft presuppositions in quantificational sentences, their interactions with scalar implicatures, and their effects on the licensing of negative polarity items. In chapter 5, I show that by looking at the interaction between presuppositions and scalar implicatures we can solve a notorious problem which arises with conditional sentences like (1) (Soames 1982, Karttunen and Peters 1979). The main issue with (1) is that it is intuitively not presuppositional and this is not predicted by any major theory of presupposition projection. (1) I’ll go, if you go too. Finally, I explore in more detail the question of which alternatives should we consider in the computation of scalar implicatures (chapter 6). Traditionally, the answer has been to consider the subset of logically stronger alternatives than the assertion. Recently, however, arguments have been put forward in the literature for including also logically independent alternatives. I support this move by presenting some novel arguments in its favor and I show that while allowing new alternatives makes the right predictions in various cases, it also causes an under- and an over-generation problem. I propose a solution to each problem, based on a novel recursive algorithm for checking which alternatives are to be considered in the computation of scalar implicatures and the role of focus (Rooth 1992, Fox and Katzir 2011). / Linguistics