My aim in this paper is to provide some introductory coordinates aiming at orienting a unified discourse on the doctrine of vagueness in Peirce. After tracing some of the stages in Peircean scholarship that have brought the concept of vagueness into focus, I will show that vagueness, as it appears in Peircean philosophy, is a three-dimensional concept. Thus, while vagueness is a concept that appears in a logical-semiotic dimension – and more specifically as a problem related to the quantification of the subject within the propositional context – it is also articulated in an epistemological and metaphysical dimension. Here I focus primarily on the semiotic dimension and suggest how an account of vagueness might hold together the epistemological and metaphysical consequences of the notion of vagueness.