The volume is a specialized selection of writings spanning almost twenty years (1894-1913) that are essential to understand Peirce's views about signs, their classification, and the relations between semiotics and logical inquiry. Peirce's extensive researches into the principles of semiotic taxonomy are well represented in this volume. The selections will be prepared following the methods of scholarly editing of philosophical texts. The preliminary work will consist in reconstructing the genealogy of the documents, dating them, selecting them, understanding their context, and editing them according to the highest editorial and philological standards. However, the resources used and the methods followed in designing it will ensure that the work will be judged by both specialists and non-specialists of high scholarly quality.