Technical Abstract: Cotton quality trash measurements used today typically yield a single value for trash parameters for a lint sample (i.e. High Volume Instrument – percent area; Advanced Fiber Information System – total count, trash size, dust count, trash count, and visible foreign matter). A Cotton Trash Identification System developed at the USDA-ARS Southwestern Cotton Ginning Research Laboratory was used to identify and size trash objects in the lint samples collected before and after lint cleaning as part of a two-year beltwide commercial cotton gin sampling project. The CTIS trash categorizations were used to develop particle size distributions (PSD) for the lint samples. These PSD were then compared to assess the effect of lint cleaning. Also, different probability density functions were explored to characterize the shape of the lint trash PSD. Typical of standard foreign matter analyses, foreign matter content was decreased by lint cleaning. Further, the data suggested that foreign matter was reduced for all particle sizes, but not at the same rate for all particles sizes. Surprisingly, though total foreign matter levels, both count and area, and maximum particle size decreased with lint cleaning, the average particle size increased.