Studies of air quality and health effects from airborne particulate matter (PM) have traditionally focused on particles <10 μm in diameter (PM10) or particulates <2.5 μm in diameter (PM2.5). The coarse fraction of PM10 (particulates >2.5 μm) has only been studied recently.This paper investigates the vertical distrubution of coarse PM at the Boulder Atmosphericc Observatory Tower located in Erie, Colorado. There were five measurement levels selected on the tower at 2, 22, 50, 100, and 300 meters. The devices used for collection of the coarse PM were a PM10 field sampler and a PM2.5 field sampler. Calculations were performed to get the concentration of PM10 and PM2.5, which then the coarse particulate (CP) concentration was obtained by subtracting the concentration of PM2.5 from PM10. We compared our measurements of the vertical distribution of coarse PM to the assumption of the Community Multi-scale Air Quality model, which assumes all particulate matter is uniformly distributed vertically in the Atmospheric Boundary Layer (ABL). From our measurements, we have shown that the concentration of CP is not always vertically uniform, and rather that it often decreases from the surface to 300 m. Further research is needed to further quantify the variability of the CP vertical profile under different scenarios. This research is important in order to get the CMAQ modeling system assumption correct in order to accurately predict the air quality of the future.