Through an historical investigation of the concept of the zero from Gauthiot to Deleuze, this paper examines a peculiar object, the signifying nothing. Saussure founds his science of linguistics on the claim that the opposition between something and nothing provides the minimal condition for the existence of language. What is this nothing and how can it be recognized? What can account for the zero—as structuralist linguists call a marked nothing—in language? The essay first considers linguists’ responses to these problems, before turning to later redeployments of the zero as the index for the fundamental questions raised by the structuralist project as such.