Law schools are offering more courses in public international law, so this volume, which explains the many principles, treaties, declarations, and other international agreements referred to by practitioners and the news media, is especially useful. The entries are substantial, averaging around a page in length, and are understandable to people unfamiliar with this area of law. The introduction to the book is lengthy and is primarily a history of the field that places entries in context. It mostly deals with actions of the United Nations, but other countries are also included. The book is helpful for those wishing to understand the ideals of international law, not as it is in actual practice. For instance, the entry on women points out that the UN has failed to meet its own goal of having 50 percent of its senior positions held by women (as of April 2017). Summing Up: Recommended. Lower-division undergraduates through faculty.