This unit describes methods for the construction and use of handheld particle bombardment devices for high-efficiency inoculation of intact plants with nucleic acids and viruses. The devices accelerate heavy metal particles coated with nucleic acids or viruses into plant tissues and are driven by pressurized gas. They are inexpensive to construct and use, and can be assembled in any laboratory. The equipment enables inoculation with full-length infectious cDNA, PCR products, virus from sap or a virus preparation, and in vitro viral transcripts. The inoculation of some phloem-limited RNA viruses is also possible. Additionally, this technology allows for inoculation of large numbers of plants (mass bombardment), inoculation of soft plants that do not survive bombardment inoculation by other means, inoculation in the greenhouse, study of viral recombination in plants, rapid promoter analysis, and monitoring of virus movement using an infectious clone bearing a reporter gene.