Current approaches of cotton improvement include the use of genetic engineering, but progress in this area is limited because of the notoriously recalcitrant tissue culture nature of most elite cotton cultivars. A well-established regeneration system is desirable for cotton improvement through genetic engineering. Our goals were to 1) screen representatives of the four cultivated Gossypium species, G. hirsutum L., G. barbadense L., G. arboreum L., and G. herbaceum L., for regenerability, 2) evaluate callus production on various media used, and 3) characterize calli of the screened genotypes with respect to morphology and other growth parameters. Two initiation media, CIM and MS2NK, and two maintenance media, CMM and L3G, were used. Forty eight lines representing the four cultivated cotton species from diverse geographic areas of the world were screened. In all accessions and media tested, hypocotyl explants were better callus producers than cotyledons. Callus production was higher on CMM than CIM medium, overall. Diploid species produced more callus than the tetraploids on both CIM and CMM, but no significant difference was observed between MS2NK and L3G. Callus morphology varied depending on genotype and hormone levels. Somatic embryos have been obtained for the documented regenerable line Coker 312 cultured either on solid or liquid media. There are no definitive indications of somatic embryos in the remainder of the accessions so far. Monthly selection, transfer, and observations are continuing.