Review of Agricultural Economics—Volume 28, Number 1—Pages 59–71 Farm-Level Economic Performance of Genetically Modified Cotton in Maharashtra, India Richard Bennett, Uma Kambhampati, Stephen Morse, and Yousouf Ismael A study of the commercial growing of Bacillus thuringiensis (Bt) cotton in India, compares the performance of over 9,000 Bt and non-Bt cotton farm plots in Maharashtra over the 2002 and 2003 seasons. Results show that since their commercial release in 2002, Bt cotton varieties have had a significant positive impact on average yields and on the economic performance of cotton growers. Regional variation showed that, in a very few areas, not all farmers had benefited from increased performance of Bt varieties. I ndia ranks third in global cotton production after the United States and China. With 9 million hectares grown in 2004/5, India accounted for approximately 20% of the world’s total cotton area and 12% of global cotton production (Cotton Corporation of India). Cotton is a very important cash crop for Indian farmers. However, average cotton yields in India have been 300 kg/ha, compared with a world average of 580 kg/ha (Sen). One major limiting factor to cotton output is damage due to insect pests, especially bollworms. In March 2002, the Indian Government allowed commercial cultivation of genetically modified (GM) Bacil- lus thuringiensis (Bt) cotton. The Bt gene produces a protein that is toxic to boll- worms. Some 29,000 hectares were planted with Bt cotton in 2002 in India, with ■ Richard Bennett is a professor of Agricultural Economics, Department of Agricultural and Food Economics, The University of Reading, UK. ■ Uma Kambhampati is a senior lecturer, Department of Economics, The University of Reading, UK. ■ Stephen Morse is a reader in Development Studies, Department of Geography, The University of Reading, UK. ■ Yousouf Ismael is a research fellow, Department of Agricultural and Food Economics, The University of Reading, UK. DOI:10.1111/j.1467-9353.2006.00273.x