RNA interference (RNAi) has the potential to make major contributions towards sustainable crop production and protection with minimal environmental impacts compared to other technologies. RNAi is being developed and exploited both within plants (i.e. host-induced gene silencing, HIGS) and/or as topical applications (e.g. spray-induced gene silencing, SIGS) for targeting pest and pathogen genes and for manipulating endogenous gene expression in plants. Chapters by international experts review current knowledge on RNAi, methods for developing RNAi systems in GM plants and applications for crop improvement, crop production and crop protection. Chapters examine both endogenous systems in GM plants and exogenous systems where interfering RNAs are applied to target plants, pests and pathogens. The biosafety of these different systems is examined and methods for risk assessment for food, feed and environmental safety are discussed. Finally aspects of the regulation of technologies exploiting RNAi and the socio-economic impacts of RNAi technologies are discussed.