Excerpt from the report Summary: This is the first report in a series of relationship studies on cotton fiber properties which deals with single-strand yarn strength. All previous studies of this series dealing with yarn-strength have involved the measure of skein strength. The two tests of yarn strength, however, differ radically in a number of particulars. Predicting equations and related information are helpful to the cotton trade and textile industry in choosing cottons best suited to the manufacture of specific products, in selecting blends of cotton for processing, and for meeting different levels of product quality. Such equations and knowledge also give assistance to cotton breeders by informing them of the fiber properties which are important to their programs. This publication gives 13 equations, based on various measures of raw-cotton quality, for predicting single-strand strength and elongation of any size of carded yarn within a relatively wide range. Ten of the equations refer to yarn strength and three to yarn elongation. The precision of estimate expected with each equation is shown.