This volume contains a collection of contemporary papers on free logic which cover a wide range of topics. These topics show that free logic is applied not only in traditional philosophical areas, but also in various contexts of modern formal logic as well as in the discussion of theoretical aspects of programming. Part I of the book covers theories of names and definite descriptions. Part II contains papers on various topics in the logic of modalities. Part III is devoted to semantics and programming. In part IV free logic is used to analyze and discuss topics from the history of philosophy. In addition, one of the founders of free logic, Karel Lambert, not only contributes an article to this volume, but he also comments the papers of all the other authors. As a result, this book should be of interest not only to philosophers and logicians, but also to computer scientists and researchers interested in foundational aspects of computer programming.