Background: The Society of Thoracic Surgeons General Thoracic Surgery Database (GTDB) has demonstrated outstanding results for lung cancer resection. However, whether the GTDB results are generalizable nationwide is unknown. The purpose of this study was to establish the generalizability of the GTDB by comparing lung cancer resection results with those of the Nationwide Inpatient Sample (NIS), the largest all-payer inpatient database in the United States. Methods: From 2002 to 2008, primary lung cancer resection outcomes were compared between the GTDB (n = 19,903) and the NIS (n = 246,469). Primary outcomes were the proportion of procedures performed nationally that were captured in the GTDB and differences in mortality rates and hospital length of stay. Observed differences in patient characteristics, operative procedures, and postoperative events were also analyzed. Results: Annual GTDB lung cancer resection volume has increased over time but only captures an estimated 8% of resections performed nationally. The GTDB and NIS databases had similar median patient age (67 vs 68 years) and female sex (50% vs 49%), lobectomy was the most common procedure (64.7% vs 79.7%; p < 0.001), and pneumonectomies were uncommon (6.3% vs 7.2%; p < 0.001). Compared with NIS, the GTDB had significantly lower unadjusted discharge mortality rates (1.8% vs 3.0%), median length of stay (5.0 vs 7.0 days; p < 0.001), and postoperative pulmonary complication rates (18.5% vs 23.6%, p < 0.001). Conclusions: The GTDB represents a small percentage of the lung cancer resections performed nationally and reports significantly lower mortality rates and shorter hospital length of stay than national results. The GTDB is not broadly generalizable. These results establish a benchmark for future GTDB comparisons and highlight the importance of increasing participation in the database.