A system of experimental and mathematical models was developed from data on grain particle transport, collected from a series of experiments in a large-scale wind tunnel, and from mathematical principles. The experimental model was derived from a FORTRAN program using the observed data. As a first attempt, it took into account the role played by the following factors in grain particle transport: the grain-size distribution, the mean diameter of the particle size class, the mean diameter of the effective surface particles, the surface mobility, friction velocity, and threshold velocity. The comparison between the observed and the predicted results indicated that the experimental model was able to predict the transport rate of grain particles in different size classes over time with good reliability. The mathematical models used in conjunction with the experimental model could be employed to calculate the variation of the mean grain size, the grain-size distribution, the approximate fluid threshold velocity, and the accumulated erosion of the particle surface over time. The experimental model should be applied with caution to natural conditions because of the assumption of a dry, loose, and large-roughness-free surface and aerodynamically dominant fluid. The mathematical models, except for fluid threshold velocity, were accurate, given a precise transport rate of grain particles in different size classes over time. ¿ American Geophysical Union 1994