Conceptual models of crop production are developed to demonstrate the applicability of the theory of natural resource extraction to the economic analysis of cropland erosion and to draw upon this theory and the theory of environmental quality to consider economic issues in cropland erosion and erosion control for water quality improvement. Based upon the conceptual analysis, a multi-period model of cropland production in a small Iowa watershed is developed to consider these same issues quantitatively. The results demonstrate the importance of dynamic analysis in the investigation of issues in cropland erosion control and provide an economic basis for choosing alternative mixes of policy measures to obtain efficient control of cropland erosion. Damage cost estimates are also developed to allow some consideration of the social gains from erosion control. Based on these, it is demonstrated that some net social gains are to be expected when erosion control is obtained by highly efficient control strategies.