The genetic resources of cotton are classified into five tetraploid species in the primary gene pool, 20 diploid species in the secondary gene pool, and 25 diploid species in the tertiary gene pool. Unlike several globally important grain crops, the Consultative Group on International Agricultural Research (CGIAR) international research and conservation centers do not actively maintain cotton genetic resources. Hence, it is the responsibility of cotton scientists around the world to develop international collaborative efforts to maintain and preserve cotton genetic resources. This paper describes a recent, collaborative effort among scientists from eight countries to document the primary global cotton genetic resources. The eight primary international cotton germplasm collections are described. These include collections in Australia, Brazil, China, France, India, Russia, Uzbekistan, and the United States.