High temperature stress adversely affects the growth, development and ultimately yield of cotton. This paper presents a general outline of studies evaluating methodologies that measure the ability of cotton to tolerate high temperatures. Simple methodologies that measured plant response to high temperature stress at different scales (field to laboratory) are being assessed for their ability to detect differences between cotton cultivars. Preliminary measurements on known heat tolerant and susceptible cultivars taken at a whole plant, leaf, cell and at the individual gene levels suggest that there is indeed variation among cultivars, and there is opportunity to detect differences in their ability to withstand high temperatures with simple laboratory tests. These methodologies are being further evaluated to establish their value in identifying thermotolerant cotton cultivars from a broader range of cotton germplasm for potential use in cotton breeding programs.