Prospective readers of this book should be informed at the outset that it is not a textbook and it is not, by and large, about immunologic incompetence. Rather it is a compilation of presentations given at a conference in 1970 by established investigators, most of them pediatricians, on that aspect of immunology about which they were particularly knowledgeable. Moreover, the book's contents encompass much more than its title implies, in that many disease states not generally ascribed to incompetence are included, and fortunately for those who seek a genuine understanding of immunology and diseases involving immune mechanisms, there is as much discussion of the basic physiology of immunity as of illness.