David Lewis's untimely death on 14 October 2001 deprived the philosophical community of one of the outstanding philosophers of the 20th century. As many obituaries remarked, Lewis has an undeniable place in the history of analytical philosophy. His work defines much of the current agenda in metaphysics, philosophical logic, and the philosophy of mind and language. This volume, an expanded edition of a special issue of the "Australasian Journal of Philosophy", covers many of the topics for which Lewis was well known, including possible worlds, counterpart theory, vagueness, knowledge, probability, essence, fiction, laws, conditionals, desire and belief, and truth. Many of the papers are by very established philosophers; others are by younger scholars including many he taught. The volume also includes Lewis's Jack Smart Lecture at the Australian National University, 'How Many Lives has Schrodinger's Cat?', published here for the first time. "Lewisian Themes" will be an invaluable resource for anyone studying Lewis's work and a major contribution to the many topics that he mastered.