Links between poverty and natural resource degradation are examined in the context of soil erosion, fertility loss and overgrazing in the Peruvian Altiplano. Multiple regression analysis of 1999 farm survey data examines 1) what agricultural practices affect natural resource degradation, and then 2) what factors affect farmers' choices of those agricultural practices. Soil erosion and fertility loss appear reduced by increased fallow in crop rotations. Overgrazing and range species loss are affected by changes in herd size and rotational grazing. The effect of investment poverty on natural resource outcomes is not clear. However, social and human capital variables both tend to favor the choice of more sustainable agricultural practices. Natural resource conservation policies that build on traditional social institutions may offer promise in areas with strong social fabric where farmers tend not to invest financially in natural resource conservation.