This article investigates the role of presuppositionality (defined as the presupposition of existence) in the second language (L2) acquisition of English articles. Building upon the proposal in Wexler 2003 that young English-acquiring children overuse the with presuppositional indefinites, this article proposes that presuppositionality also influences article (mis)use in adult L2 acquisition. This proposal is supported by experimental results from the L2 English of adult speakers of Korean, a language with no articles. The experimental findings indicate that presuppositional indefinite contexts trigger overuse of the with indefinites in adult L2 acquisition, as in child L1 acquisition (cf. Wexler 2003). The effects of presuppositionality are teased apart from the effects of other semantic factors previously examined in acquisition, such as scope (Schaeffer and Matthewson 2005) and specificity (Ionin, Ko, and Wexler 2004). The results provide evidence that overuse of the in L2 acquisition is a semantic rather than pragmatic phenomenon. Implications of these findings for overuse of the in L1 acquisition are discussed. This article also has implications for the study of access to Universal Grammar in L2 acquisition, as well as for the number and type of semantic universals underlying article choice crosslinguistically.