The goal of this project is to compare the efficacy of lung screening in community practice with that reported in the National Lung Screening Trial (NLST) with respect to the rate and type of abnormalities suspicious for lung cancer, the rate and type of significant incidental findings that are seen on lung screening and may be clinically important, but that are not related to lung cancer, and the diagnostic testing that is done to evaluate lung and other abnormalities. We will use this information to compare the cost effectiveness of community lung screening with that estimated from the NLST and provide information that can be used to enhance the effectiveness of lung screening in the community.