Discrete element modeling was used to establish the effects of size distribution on loose packing fraction during the fall of 5000 to 10 000 agglomerates. Monosized distributions exhibited slightly lower packing fraction than "narrow" distributions. However, broad distributions always produced the lowest packing fraction. The application of radius ratio rules had an effect opposite to that intended. Smaller fines had a disproportionately large effect on packing fraction, an effect attributed to gaslike behavior, Gravity-driven random packing in ceramic agglomerates was governed by a combination of "bridge" formation and kinetic agglomerate-agglomerate interactions, not by geometric constraints.