The law of international responsibility, a classic area of investigation in international law, has been attracting an ever increasing interest in recent times, as reflected also in the work of the International Law Commission on State responsibility and on responsibility of international organizations. The exploration of current trends in this important area is therefore an appropriate and timely subject for a book in memory of Oscar Schachter, a former United Nations official, Columbia Law School professor, ASIL President, and international lawyer of world-wide reputation, who died in December 2003. The editor of the book has assembled a team of thirty-six prominent international lawyers belonging to twenty different nationalities to write about different aspects of the law of international responsibility, from general issues to specific areas of the law (including responsibility before international courts and tribunals), with respect to both the law of State responsibility and responsibility of international organizations and other non-State actors. The result of this effort is a monographic volume (enriched by a biography and a list of publications of Oscar Schachter, and accompanied by a bibliography of all the works cited in the various contributions and an index for easier consultation), which will be of interest not only to the many admirers and friends of Oscar Schachter around the world, but also, more broadly, to international law academics and practitioners.