This book includes the proceedings of a NATO Advanced Study Institute held at Washington State University, Pullman, Washington from July 26 until August 6, 1982. Although genetic engineering in eukaryotes is best developed in yeast and mammalian cells, the reader will find that some emphasis has been put on plant systems. Indeed, it was our position that the development of plant cell genetic transformation would benefit from the interactions between a comparatively smaller number of fungal and animal cell experts and a larger number of plant cell specialists representing various aspects of plant molecular genetic research. On the other hand, it is clear that the ultimate achievements of plant genetic engineering will have a tremendous ~pact on, among other things, food production without generating the problems of ethics encountered when one contempla-tes the genetic modification of human beings. Therefore, this slight bias in favor of the plant kingdom simply reflects our belief that a "second green revolution" will benefit mankind to a greater extent than any other kind of genetic engine ering. The keynote lecture of the Institute was delivered by Dr. John Slaughter, Director of the National Science Foundation, whom we deeply thank for his words of encouragement and commitment to the genetic manipulation of plants.