Invasive species are a growing threat in the United States, causing losses in biodiversity, changes in ecosystems, and impacts to economic enterprises such as agriculture, forestry, fisheries, power production, and international trade. The costs of preventing and controlling invasive species are not well understood or documented, but estimates indicate that the costs are quite high, in the range of millions to billions of dollars per year. EPAÃ¢â‚¬â„¢s Office of Water needs to develop a national estimate of the costs of aquatic invasive species and the benefits of control. This review of the economic literature on invasive species is the first stage in the development of that estimate. The review includes studies on fish, mollusks, crustaceans, invertebrates, and plants.