The ability to cut and join DNA to create a new molecule and to insert into the crop plant the new DNA molecule as a new gene, a “transgene,” forms the basis of the most revolutionary crop improvement technology of the 20th century. The bulk of crop transgenes thus far commercialized were designed to aid in crop protection against insects and weeds. The first commercial introduction of transgenes into field crops occurred in 1996. By 2000 in the United States, transgenic soybean and cotton accounted for more than half the area planted to these crops. Cotton accounts for virtually all current transgenic crop planting in California. This article compares transgene-based and ...