Solid particles of nonuniform sizes exhibit behaviors not seen in monodisperse distributions. Following a previous study of monodisperse particles, the goal of this study is to investigate effects of a binary-size distribution on erosion of lunar soil from a rocket landing. The discrete element method is used to examine near-field (near impingement) and far-field behavior. For near-field simulations, small particles preferentially collide with large particles from below, due to a difference in velocity caused by gas forces, which is analogous to behavior for entrainment in gas-solid fluidized beds. These collisions cause vertical momentum transfer from small to large particles that affects species and total erosion flux. For far-field simulations, collisions result in an increase in vertical dispersion (binary) and a reduction in maximum horizontal velocity (binary and monodisperse). These results have implications on the most appropriate modeling framework to use for predictions over large distances utilizing wide size distributions. (c) 2015 American Institute of Chemical Engineers AIChE J, 62: 984-995, 2016