Publisher Summary All the cottons of the world, whether cultivated or wild, belong to the genus Gossgpium. For convenience, they may be divided into three main groups: Old World or Asiatic cultivated (n=13), New World or American cultivated (n=26), and Wild (n=13, with one anomalous exception). This chapter discusses the procedures and methods of breeding American cultivated cottons, more particularly to work with the American Upland types. The cultivated varieties of cotton in the United States fall into the New World group that is characterized by 26 pairs of chromosomes. The cultivated American cottons are of two species: (1) G. hirsutum, commonly called Upland cotton, and characterized as an annual subshrub with few or no vegetative branches with short to medium long and coarse to medium fine fibers borne on seeds within relatively large, rounded, usually 4 to 5 loculed capsules (bolls), (2) G. barbadense, commonly referred to as American-Egyptian and Sea Island cotton. Agricultural varieties of this species are inherently perennial shrubs, but they usually behave as annuals under American Cotton Belt conditions. Relatively long, fine fibers are borne on seeds within small to medium, tapering usually 3 to 4 loculed capsules.