RNA interference (RNAi) is a powerful method used to silence gene expression, and has been proved an effective tool in a wide variety of organisms. Ideal for the upper-level undergraduate and graduate student, or for use as a professional reference, this book helps readers understand the history of RNAi and how it can be applied to model organisms. It begins with a thorough explanation of the history of RNAi and its applications in common model organisms with an emphasis on the experimental design. Readers will then develop practical proficiency through hands-on experiments in tobacco plants, in the soil worm, C. elegans, and in mammalian cell cultures. Using these three systems, readers and practitioners will have the opportunity to asses the extent of gene silencing using both qualitative and quantitative methods which measure messenger RNA and protein levels.