Technical Abstract: Air quality in communities surrounding cattle feedlots is a growing public concern. Our objective was to quantify emission patterns and weather effects on particulate matter (PM) transport upwind and downwind from two large cattle feedlots (KS1, KS2) in Kansas. The concentrations of PM2.5 (particles = 2.5 microns), PM10 (particles = 10 microns), and TSP (total suspended particles) upwind and downwind of were measured with gravimetric samplers from May 2006 to October 2009 (at KS1) and from September 2007 to April 2008 (at KS2). The downwind and net (i.e., downwind – upwind) mass concentrations of PM2.5, PM10, and TSP varied diurnally and seasonally, indicating the need for multiple-day, seasonal sampling. The downwind and net concentrations of all PM classes as well as the downwind PM2.5/PM10 and PM2.5/TSP ratios were influenced by the surface moisture content of the cattle pen, humidity, temperature, and barrometric pressure. Measurement of the downwind particle size distribution with a cascade impactor showed geometric mean diameters ranging from 7 to 18 µm, indicating that particles that were emitted from the feedlots were generally large in size. This study provides valuable air quality information needed by farmers, animal scientists, engineers, and regulatory officials striving to develop economically viable, environmentally benign, and socially acceptable animal management practices.