PURPOSE: To compare sublobar resection and stereotactic body radiation therapy (SBRT) in patients with stage I non-small cell lung cancer (NSCLC). METHODS: Patients undergoing sublobar resection or SBRT for stage I NSCLC from 2007 to 2014 at Duke University Medical Center were evaluated. The primary endpoint of interest was freedom from local recurrence. Kaplan-Meier survival estimates and Cox proportional hazards multivariate analyses were performed. RESULTS: 221 patients with stage I NSCLC undergoing sublobar resection (n = 151; 105 wedge and 46 segmentectomy) or SBRT (n = 70) were evaluated. The majority (89%) of patients receiving SBRT were medically inoperable, and compared with surgical patients, were significantly older (74 vs 70 years, p = 0.019), had higher Charlson Comorbidity Indices (3.7 vs 2.7, p < 0.001), larger tumors (2.4 cm vs 1.7 cm, p < 0.001), and worse baseline pulmonary function. At 3 years, freedom from local recurrence was 90% (95% CI 82-94%) for surgery and 85% (95% CI 65-94%) for SBRT (p = 0.71). While overall survival and disease-free survival were higher in the surgical cohort, no differences were noted in cancer-specific disease-free survival (60% vs. 65%, p = 0.84). On multivariate analysis, higher Charlson Comorbidity Index (HR 1.38, 95% CI 1.19-1.61, p < 0.001) and lower diffusion capacity (HR 0.97, 95% CI 0.96-0.98, p < 0.001) were independently associated with inferior overall survival. No differences in overall survival between surgery and SBRT (HR 1.20, 95% CI 0.74-1.95, p = 0.46) were observed after correcting for baseline imbalances in prognostic factors. CONCLUSIONS: SBRT and sublobar resection provided similar rates of local tumor control and overall clinical outcomes in stage I NSCLC.