The Uster® High Volume Instrument (HVI®) is used in the U.S. to classify cotton, including cotton color. The cotton color parameters measured on the HVI are Rd (diffuse reflectance) and +b (yellowness). Comments from industry have indicated that some cotton bales appeared to have changed significantly in +b (yellowness) from their initial HVI color measurements. As a result of these reports, there was interest in "on-site"/remote location measurements of cotton color that will yield "real time" color values, with emphasis on yellowness. A program was implemented to develop portable color spectrophotometer procedures and protocols to perform rapid, precise, and accurate cotton fiber color measurements at-line in remote locations and to interface those results into the Cotton Incorporated Engineered Fiber Selection® (EFS®) System MILLNet™ software. AMS standard tiles, cotton samples, and routine cotton samples were used to perform comparative evaluations to establish the relationships between the HVI Rd and +b and portable spectrophotometer L*a*b* color parameters. The best correlations were achieved between 1) the HVI +b and portable spectrophotometer b* and 2) the HVI Rd and spectrophotometer Y. Excellent comparative results were obtained and all end-state criteria were achieved (high R2s, low spectrophotometer analytical variability, and a low number of outliers). The HunterLab MiniScan EZ (MSEZ) results were interfaced with the EFS System MILLNet™ software, and preliminary field trials were performed on more than 400 bale samples at a non-U.S.-based mill. Very good color agreement was observed between the mill’s HVI unit and the MSEZ- MILLNet™ system, with distinct and significant +b color shifts detected.