Embryogenic cell suspensions of cotton (cv. Coker 312) were sieved to obtain a fine fraction. This fraction was then subjected to severe growth limiting high and low temperature stress for selection of resistant variants. Cells were placed in a controlled temperature incubator for various periods of time at either 45 C, 40 C, or 50 C to determine ak desirable time/temperature exposure to obtain a severely limiting but not unrecoverable stress for the cell lines. Cells resistant to high temperature were then selected using three methods: continuous exposure at 45 C for 10 hours, three hour pulses at 45 C at 24 hour intervals until 100 hours of stress were accumulated, three hour pulses at 45 C at 24 hour intervals until 75 hours of stress were accumulated followed by exposure to a lethal temperature of 45 C for 24 hours. Cell lines were maintained in the absence of stress for 5 sub-cultures prior to retesting for increased resistance to temperature stress. When tested, significant increases in cell viability over the control line were noted for all methods of selection. Plants have been regenerated from all selected cell lines.