Tomato spotted wilt virus (TSWV) causes serious diseases of many economically important plants representing 35 plant families, including dicots and monocots. This wide host range of ornamentals, vegetables, and field crops is unique among plant infecting viruses. Another unique feature is that TSWV is the only virus transmitted in a persistent manner by certain thrips species. At least six strains of TSWV have been reported; the symptoms produced and the range of plants infected vary among strains. Although previously a threat only to crops produced in tropical and subtropical regions, today the disease occurs worldwide, largely because of wider distribution of the western flower thrips and movement of virus-infected plant material. Early and accurate detection of infected plants and measures to reduce the vector population are discussed as critical steps for disease control.