There has been a rapid expansion in the commercial cultivation of genetically modified crops, rising from the first plantings in 1995 to 44.5 million hectares worldwide in 2000, most of which have grown in North America. Though there are sharp divisions in opinions on benefits and risk, genetic modification (GM) does not represent a single, homogenous technology. Each application brings different potential benefits and risks for different stakeholders. This paper reviews recent scientific progress and future applications using a new typology of three generations of genetically modified organisms (GMOs) ranged against five types of scientific application. Agricultural GMOs pose a range of potential environmental and health risks. An analysis of recent independent field and scientific evidence from industrialized countries summarizes the current state of knowledge on seven types of risk that apply to all agricultural systems: (1) horizontal gene flow; (2) new forms of resistance and pest problems; (3) recombination to produce new pathogens; (4) direct and indirect effects of novel toxins; (5) loss of biodiversity from changes to farm practices; (6) allergenic and immune system reactions; and (7) antibiotic resistance marker genes. There remain highly contrasting positions taken by different stakeholders over GMOs. A review of three debates explains claims and counter-claims for (1) genetic modification as technological fix or contributor to sustainability; (2) genetic modification as driver of corporate power or friend of farmer; and (3) genetic modification as feeder of the world or eliminator of alternatives.