||Little more than a decade ago, the development of host plant resistance to maize insects was considered to be a very difficult, if not impracticable, goal of plant breeding, and in some quarters doubts about its feasibility were strong enough to discourage any serious and sustained effort to breed for insect-resistant germplasm. Fortunately, a number of scientists were more optimistic about the prospects of such work and labored diligently to establish its foundation. The outcome of their efforts was an array of techniques for mass rearing of insects and for artificially infesting maize on a large scale, which are prerequisites for effective screening of germplasm for resistance. Using those techniques, maize researchers in the USA have been able to identify insect resistant germplasm, and it has been adopted by the breeding programs of various seed companies, some of which report that the resistance has been incorporated into hybrids now being made available to farmers. More recently, insect resistant germplasm of subtropical and tropical adaptation has been developed at CIMMYT in the form of specialpurpose populations and is in the initial stages of testing and dissemination to national maize programs in the Third World. The pace at which that germplasm is incorporated into elite materials for release to developing country farmers now depends very much on national programs. As with much previous work on host plant resistance to insects, methodology is the key. It is imperative that a growing number of national programs acqUire the capacity to mass rear insects, infest the maize crop with them, and select efficiently for resistance, so that they can take full advantage of the resistant germplasm that is being made available. The symposium reported here was organized to assist developing country scientists as they go about that urgent task. This publication contains a wealth of detailed information on the whole range of rearing, infesting, and breeding methodologies and is extensively illustrated. It should be a useful reference work for various groups, including agriculture students and professors as well as staff of national maize programs, both beginners and seasoned veterans. Since the progress made so far in developing insect-resistant germplasm has been due in large part to cooperation among various institutions, we decided that any effort to compile the available knowledge and experience should also be a cooperative effort. We therefore invited a large group of authorities on maize insects to describe the methodologies and equipment they have developed and employed in their host plant resistance studies. The contributors were encouraged to provide plenty of details and illustrations, so that readers would stand a good chance of being able to repeat the procedures. We also invited scientists from South America, Africa, and Asia to report on maize insects and entomology work in their countries, so that we could convey in this volume some sense of the current status and future prospects for the development of host plant resistance in the Third World. Of course, much of that information is already available in other forms, but we felt that it would be even more useful and accessible, particularly to colleagues in the Third World, if it were brought together to form a single publication. We are extremely grateful to all participants for their contributions, to the United Nations Development Programme (UNDP) and the US Agency for International Development (USAID) for providing funds that enabled us to organize the workshop and bring the participants to Mexico, and to West Germany's Agency for Technical Cooperation (GTZ) for paying the costs of the Proceedings. We trust that the efforts of all of those individuals and organizations will be amply rewarded through more widespread and effective work on host plant resistance to maize insects, resulting in superior germplasm products for developing country farmers.