Once widely recognized as a leading twentieth-century philosopher, Clarence Irving Lewis has been largely forgotten in the minds of contemporary philosophers. Though Lewis has never been without his defenders, such as Roderick Firth and Sandra Rosenthal, and there are signs of a nascent Lewis renaissance (e.g., recent works by Murray G. Murphey and Cheryl Misak), he is more commonly confused with David Lewis or C. S. Lewis than remembered for his philosophical views. Given the neglect of Lewis's work, our introduction will address two questions: What has caused Lewis to be largely forgotten, and why is a Lewis revival in order?