Technical Abstract: The effects of various machine-fiber interactions during harvesting and ginning on fiber quality and attachment between foreign-matter particles and fibers were studied to develop new and less damaging methods for removing foreign-matter particles from cotton fiber. In total, the study involved 75 samples collected from five locations in a field near College Station, Texas, including three replications and five different harvesting and processing treatments: (1) hand-picked and hand-ginned, (2) machine-picked and hand-ginned, (3) machine-picked, seed-cotton-cleaned, and hand-ginned, (4) machine-picked, seed-cotton-cleaned, and machine-ginned, and (5) machine-picked, seed-cotton-cleaned, machine-ginned, and one-stage lint-cleaned. A microscope was used to identify foreign-matter particles in each sample. Physical characteristics of the particles and their attachment to fibers were investigated and classified. All samples were analyzed with HVI and AFIS. Data of the particle classification, HVI, and AFIS were statistically processed with SAS. Results indicated that each machine-fiber interaction during the harvesting and ginning process had the net effect of decreasing the size of foreign-matter particles. The particles had no obvious difference in shape across the processing stages. The tightness of particle-fiber attachment, the number of neps, and the short fiber content differed significantly as a function of mechanical actions; they all tended to increase as the number of mechanical actions increased. As expected, the gin stand was a major contributor to the increase in short fiber content. The majority of the foreign-matter particles were leaves, but proportions of the particle categories changed with stages of processing. The proportion of leaf particles decreased, while the proportion of seed-coat fragments and stems increased, with an increasing number of mechanical actions.