Field infiltration behavior of a fine loamy mixed mesic, Typic Haplaquoll, was related to indices of surface microrelief and rainfall energy using simulated rainfall and ponded water. Infiltration of simulated rainfall was controlled primarily by a surface crust. Rainfall-since-tillage was a good index of the energy required to develop a crust. Indices of surface roughness were useful in predicting the effectiveness of crusts in restricting infiltration, especially when the surface was protected from rainfall energy. Crusts also developed on surfaces with rough microrelief. Several indices of surface roughness and spatial dependence of surface height were used to describe surface microrelief. A new procedure is proposed for determining both oriented and random roughness from microrelief height data. Tillage orientation is explicitly considered in determining the modified roughness index. Statistically, all indices of surface roughness examined in this study were similar in describing surface roughness effects on infiltration.