It was the goal of the authors to create a set of reference cottons for maturity measurements. To achieve this they selected 104 cotton bales representing the two principal cultivated species. The vast majority of the bales originated in the USA, but some foreign-grown cotton bales were also selected (Egypt, Uzbekistan, Pakistan, Cameroon, Syria, Benin, and Australia). A representative sample of approximately 30 kg (70 pounds) was taken from each bale. Each sample was homogenized according to the protocol used by the International Cotton Calibration Standard Committee (ICCSC) to produce reference cottons. Eight sub-samples per bale were taken and a minimum of 500 cross-sections per sub-sample were analyzed. A broad range of average values of fiber perimeter and fiber maturity for the 104 bales were obtained. Evaluation of the mathematical and statistical relationships pertinent to maturity and fineness revealed that four critical criteria for adequate calibration standards were met. Therefore, this population of bales constitutes a good base for the calibration of the indirect measurement instruments for maturity and fineness.