The National Crop Loss Assessment Network (NCLAN) consists of a group of organizations cooperating in field work, crop modeling, and economic studies to assess the immediate and long-term consequences of air pollution on crop production. Two primary objectives are (1) to define relationships between yields of major agricultural crops and doses of ozone, sulfur dioxide, nitrogen dioxide, and mixtures of these pollutants under realistic field conditions and (2) to use these relationships to assess the consequences of these pollutants throughout the United States. The strategy for completing the economic assessment includes developing and extrapolating a comprehensive set of dose-response data for use in an economic model to estimate effects of crop yield changes on producers and consumers.