Technical Abstract: A beltwide commercial cotton gin sampling project was initiated for the 2005-06 and 2006-07 ginning seasons to assess the changes in upland cotton quality during the ginning process and throughout the ginning season. The Cotton Trash Identification System (CTIS) developed at the USDA-ARS Southwestern Cotton Ginning Research Laboratory in Mesilla Park, New Mexico was used to identify trash objects in the cotton samples collected for the study. The objective of this project was to compare CTIS trash categorization with Advanced Fiber Information System (AFIS), High Volume Instrument (HVI), and Micro Dust and Trash Analyzer 3 analysis. Particle size distribution histograms similar to those generated by AFIS were generated for the acquired cotton images. CTIS average size, dust count, trash count, and total count measurements were compared with the AFIS measurements and CTIS measurements were also evaluated against HVI measurements for percent trash. The results showed that the CTIS measurements identified more smaller trash objects than HVI. There was poor correlation of % trash, dust count and trash count measurements among AFIS, HVI and CTIS systems. These results were inconsistent with previous results. Future work will focus on how to increase the reliability and reproducibility of the measurements, which will involve determining the optimal number of reps required for analyses. To this end, the question of whether comparisons of CTIS, HVI, MTDA, and AFIS data are valid must be explored.