This study uses a multi-region, multi-sector world trade model to estimate the impacts of Bt cotton adoption in multiple countries: the United States, China, India, Australia, Mexico, Argentina, and South Africa. Results include impacts on cotton prices, production, agricultural employment, agricultural chemical use, returns to agricultural landowners, and bilateral trade flows. The model also estimates economic impacts on related sectors of the economy. This includes, not only impacts of other agricultural production sectors, but also related, “downstream” sectors. For example, it estimates the impacts of Bt cotton adoption on production, prices, employment, and trade in the textile and the apparel industries.