Increasing land scarcity forces Rwandan farmers to expand the area under food crops at the expense of pasture, fallow, and forest. Since the non-cropping uses of land provide more vegetative cover against erosion than most food crops, land scarcity appears to be associated with unsustainable land uses. However, demographic pressure also pushes farmers to grow crops in dense associations, which increases vegetative cover on cultivated fields. The estimated relationship between farm size and protective crop cover depends crucially on how the measure of vegetative cover is adjusted to account for high cropping densities. Without any adjustment, the association between land scarcity and erosive land use is strong; with the adjustment used here, it disappears, except for high altitude areas, where bananas, the only major food crop that protects land well against erosion, do not grow well.