Technical Abstract: An assessment of the potential impact of climate change and the concurrent increase of atmospheric CO2 concentration on eastern Washington State agriculture was conducted. Climate projections from four selected general circulation models (GCM) were chosen, and the assessment included the crops with larger economic value for the state (apples, potatoes, and wheat). To evaluate crop performance, a cropping system simulation model (CropSyst) was utilized using historical and future climate sequences. Crops were assumed to receive adequate water (irrigated crops), nutrients, and control of weeds, pests and diseases. Results project that the impact of climate change on eastern Washington agriculture will be generally mild in the short term (i.e., next two decades), but increasingly detrimental with time (potential yield losses reaching 25% for some crops by the end of the century). However, CO2 elevation is expected to provide significant mitigation, and in fact result in yield gains for some crops. The combination of increased CO2 and adaptive management may result in yield benefits for all crops. One limitation of the study is that water supply was assumed sufficient for irrigated crops, but other studies suggest that it may decrease in many locations due to climate change.