The title of this article is the sub-title of Adam Watson's book, and is, I hope, just as helpful in describing the scope of the article as it is in explaining what the book is about. Each of the six books considered here is concerned with communication between states at a variety of levels, with the effectiveness of the dialogue, and with possibilities for the future. I intend first to discuss them briefly and then to consider some of the problems involved in diplomacy, and the extent to which light is thrown on them by these worthy volumes.