Background: Concurrent chemoradiation therapy (cCRT) has been shown to improve survival outcomes among inoperable stage III non-small cell lung cancer (NSCLC) patients compared to sequential CRT (sCRT) and single-modality therapy in clinical trials. However, many “real world” patients do not receive CRT, and less is known about the survival benefits of concurrent CRT vs other treatment modalities in pragmatic, non-clinical trial settings. Methods: We used the National Cancer Database (2004-2011) to identify unresected stage III NSCLC patients (ages 18-79 years) with Charlson comorbidity score ≤1 and 5-year follow up through the end of 2016. cCRT was defined as the initiations of chemotherapy (CT) and radiation therapy (RT) that were ≤14 days (n = 30,290) apart, whereas sCRT was defined as > 14 days apart (total n = 10,596). The remaining three treatment groups included CT only (n = 11,216), RT only (n = 7,772), and neither CT/RT during first course treatment (n = 10,694). Cox proportional hazard model was used to examine the 5-year survival by treatment modalities, controlling for patient demographics, comorbidity score, health insurance, facility type, area-level social deprivation index (SDI, a composite measure for area-level socio-economic status), driving time to the treatment facility, diagnosis year, and region. Adjusted hazard ratios (HR), and medium survivals were generated by treatment modalities. Results: Among 70,568 unresected stage III NSCLC patients, 61,487 (87.1%) patients died within the 5-year follow-up period. In adjusted analyses, cCRT and sCRT had similar survival (median survivals: 15.3 months), whereas other treatment modalities were associated with worse survival compared to cCRT: CT only (median survival: 10.8 months; HR [95%CI]: 1.46 [1.43-1.50]), RT only (median survival: 6.7 months; HR [95%CI]: 1.93[1.88-1.99]), and no treatment (median survival: 3.2 months; HR [95%CI]: 2.64 [2.58-2.71]), all p < 0.001. Higher comorbidity score (Charlson score 1 vs 0, HR [95%CI]: 1.18 [1.16-1.21]), non-private insurance (Medicaid: 1.16 [1.12-1.20]; Medicare: 1.10 [1.08-1.13]; uninsured: 1.21 [1.16-1.26]) were all associated with worse survival (all p < 0.001). Conclusions: Concurrent CRT and sequential CRT have similar survival outcomes among unresected stage III NSCLC patients with minimum comorbidities, however, single modality and no therapy are associated with much poorer survival among “real world” patients, and should be avoided unless clinically appropriate.