C. I. Lewis (1883--1964) was one of the most important thinkers of his generation. In this book, Sandra B. Rosenthal explores Lewis's philosophical vision, and links his thought to the traditions of classical American pragmatism. Tracing Lewis's influences, she explains the central concepts informing his thinking and how he developed a unique and practical vision of the human experience. She shows how Lewis contributed to the enrichment and expansion of pragmatism, opening new paths of constructive dialogue with other traditions. This book will become a standard reference for readers who want to know more about one of American philosophy's most distinguished minds.