The development of technologies that allow the introduction and functional expression of foreign genes in plant cells has extended in less than two decades to the production of transgenic plants with improved insect and disease resistance, seeds and fruits with enhanced nutritional qualities, and plants that are better adapted to adverse environmental conditions. Vaccines against serious human diseases and other important products have also been developed using transgenic plants. Many more agronomic and quality traits are currently being engineered in both academic and industrial laboratories, which are limited only by our poor knowledge of plant gene function. The emergence of new functional genomic strategies for the identification and characterization of genes promises to provide a wealth of information with an enormous potential to enhance traditional plant breeding and to genetically engineer plants for specific purposes. This chapter describes some of the highlights in the development of these technologies and some of the major achievements in production and commercialization of transgenic crops. We also discuss some of the biosafety issues related to release of this novel class of plants into the environment.