In this paper, I introduce a new theory of assertoric content. By 'theory', I mean both an extensionally correct definition and an elucidation of the mechanisms underlying assertoric content. In agreement with some existing work on the topic, I contend that assertoric content spans several content categories and is possibly constituted by an utterance's standing content and explicature. I also offer a detailed explanation of how and why assertoric content can be determined by an utterance's particularized conversational implicature. I call my view the first-fill theory. This theory integrates recent developments in the literature related to the lying/misleading distinction. Additionally, my view accounts for intuitive judgments regarding the assertoric content of utterances that involve slips of the tongue. Finally, I also elucidate the apparent complexity of assertoric content by drawing parallels between the interpretative modes underlying it and those used in legal interpretation.