This study explores the role of what I call metalinguistic-semantic competence (MSC) in the processes of utterance interpretation, and in some cases expression interpretation. MSC is so-called because it is grounded in a speaker's explicit knowledge of (or beliefs about) the lexically-encoded meanings of individual words. More specifically, MSC derives, in part, from having concepts of words--or conceptsW as I distinguish them--whose representational contents, I propose, are corresponding items in a speaker's mental lexicon. The leading idea is that once acquired speakers use their conceptsW to form explicit beliefs about the meanings of words in terms of which extralinguistic concepts

those words can (and cannot) coherently be used to express in ordinary conversational situations as constrained by their linguistically-encoded meanings. Or to put the claim differently, I argue that a speaker's explicit conception of word-meanings is a direct conscious reflection of his/her tacit understanding of the various ways in which lexical meanings guide and constrain without fully determining what their host words can (and cannot) be used/uttered to talk about in ordinary discourse. Such metalinguistic knowledge, I contend, quite often plays crucial role in our ability to correctly interpret what other speakers say. The first part of this work details the cognitive mechanisms underlying MSC against the backdrop of a Chomskyan framework for natural language and a Fodorian theory of concepts and their representational contents. The second part explores three ways that MSC might contribute to what I call a speaker's core linguisticsemantic competence. Specifically, I argue that MSC can help explain (i) how competent speakers acquire conceptually underspecified words with their lexical meanings, (ii) the contextual disambiguation of inherently polysemous words, and (iii) the informativeness of true natural language identity statements involving coreferential proper names. The philosophically relevant conclusion is that if any of these proposals pan out then MSC constitutes a proper explanandum of semantic theory, and hence any complete/adequate theory of semantic competence.