Charles S. Peirce (1839–1914) is widely recognized as America’s greatest philosopher, the originator of pragmatism, and one of the founders of modern mathematical logic. He was also a pioneer in the field of "semiotics," the general theory of signs, and many have regarded him as the father of the contemporary form of the discipline. The volume is a specialized selection of unpublished writings spanning almost twenty years (1894–1913) that are essential to understand Peirce’s views about signs, their classification, and the relations between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. It comprises twenty-two selections, a historico-critical introduction, and an apparatus of editorial annotations. The selections are prepared following the methods of scholarly editing of philosophical texts. The book will be of interest to graduate students and researchers working in areas such as Peirce studies, the history of American philosophy and pragmatism, logic and history of logic, the history of analytic philosophy, philosophy of language, semiotics, and language sciences.