Background: Treatment delays in lung cancer care in the United States may be attributable to a diverse range of patient, provider, and institutional factors, the precise contributions of which remain unclear. The objective of our study was to use the National Cancer Database to investigate specific predictors of increased time-to-treatment initiation. Methods: We identified 567 783 patients undergoing treatment for stage I to stage IV non–small cell lung cancer during 2010 to 2018. Time-to-treatment initiation was defined as the number of days from radiologic diagnosis to initiation of first treatment. We used mixed effect negative binomial regression to determine predictors of time-to-treatment initiation. Results: We noted a steady rise in the overall mean time-to-treatment initiation interval from 33 days (2010) to 39 days (2018; P < .01). Black race, a later year at diagnosis, nonprivate insurance, and diagnosis and treatment at different facilities were independent predictors of increased time-to-treatment initiation, irrespective of disease stage. Compared with White race, Black race corresponded to a 15% to 20% increase in time-to-treatment initiation, depending on disease stage (P < .01). For stages I and II, radiation as first course of therapy corresponded with a 69% and 33% increase in time-to-treatment initiation, respectively, compared with surgery (P < .01). Conclusions: Lung cancer treatment initiation times have seen an upward trajectory in recent years. Black patients encountered significantly longer treatment initiation times, regardless of treatment modality or disease stage. Prolonged initiation times appear to contribute to existing health care disparities by disproportionately affecting medically underserved communities.