A compilation of papers presented at the 1999 European Summer Meeting of the Association for Symbolic Logic, Logic Colloquium '99 includes surveys and research articles from some of the world's preeminent logicians. Two long articles are based on tutorials given at the meeting and present accessible expositions of current research in two active areas of logic, geometric model theory and descriptive set theory of group actions. The remaining articles cover current research topics in all areas of mathematical logic, including logic in computer science, proof theory, set theory, model theory, computability theory, and philosophy.