Bacillus thuringiensis (Bt) provides one of the most prominent biologically based pesticides. Bt affords a high degree of safety to the environment, non-target organisms and humans in combination with its effectiveness in controlling numerous insect pests. These features fill a pressing need to produce food and fiber for a growing population without eroding environment and health. Extensive safety testing and a history of human exposure without adverse effects have proven Bt to be one of the most important reduced risk pesticides. Not only is Bt effective against targeted pests, but it is safe enough to humans to be exempted from many of the precautions that apply to conventional synthetic chemical pesticides.