The travel distances of particles ranging in size from 2.88 mm to 10.63 mm were investigated in laboratory simulations of interrill overland flow. Using travel distances scaled for differences among the experiments in flow and rainfall energy, a relationship between distance traveled and particle size is obtained that shows a steep reduction in travel distance with increase in particle size. Travel distance is the outcome of two probabilities: that of moving and that of coming to rest. In interrill flow, the former is controlled by rainfall energy, but the latter is controlled by flow energy. Analysis of subsets of the data in which only rainfall or flow energy varied shows that the steep reduction in travel distance with particle size is primarily due to sensitivity to flow energy. Although particle movement (entrainment) by rainfall energy does vary with particle size, the sensitivity is less. ¿ 1998 American Geophysical Union