The overall goal of this study is to measure the effect of the impact that genetically modified cotton varieties have had on the production efficiency of small holders in farming communities in China. We also find that the adoption of Bt cotton varieties leads to a significant decrease in the use of pesticides. Hence, we demonstrate that Bt cotton appears to be an agricultural technology that improves both production efficiency and the environment. In terms of policies, our findings suggest that the government should investigate whether or not they should make additional investments to spread Bt to other cotton regions and to other crops.