This book describes the major achievements made in the R&D of transgenic insect pest-resistant cotton under the financial support of the Ministry of Science and Technology for the National High-Tech Program (863 Program), which resulted in the development of first biotechnology product applied in Chinese agriculture. The production area of Bt cotton in 2003 was accounted for more than 60% of the total acreage of cotton in China. The book contains 14 chapters in which the following aspects are described in details, including: the structure and function of the insecticidal proteins of Bt and cowpea trypsin inhibitor (CpTI) and its coding genes; the construction of plant expression vectors; the protocols for cotton transformation; the bioassays of insect pest-resistance and molecular characterization of transgenic cotton plants; the Bt transgene inheritance and breeding of elite cotton varieties; the integrated pest management for Bt cotton and monitoring resistance development in cotton bollworm population; and the environment and food safety assessment of Bt cotton, etc. In addition, the progress has been made and the future perspectives in the genetic engineering of cotton for enhancement of fungal disease resistance and improvement of fiber quality are also described and discussed.