Background: Evidence is conflicting as to whether enrollment in therapeutic drug trials confers a survival benefit for NSCLC patients. We assessed the effect of CT participation on overall survival in a cohort of metastatic NSCLC patients treated at a single large academic center. Methods: We retrospectively revised medical records of patients with metastatic NSCLC diagnosed between 1/1/2007 and 12/31/2015 that received treatment at the Seattle Cancer Care Alliance. Eligibility criteria included receipt of ≥ 1 anti-cancer drug within 180 days of M1 diagnosis, no active second malignancy, and 60 day minimum survival. We abstracted patient sociodemographic characteristics, smoking history, ECOG score, tumor histology, EGFR and ALK status, presence of brain metastases, systemic treatment history up to 5 lines, drug trial enrollment, and trial characteristics. We obtained death dates from the Washington State cancer registry complemented by medical records, censoring patients that were alive at end of follow-up (3/7/2019). We used multivariate Cox regression to test whether enrollment in ≥ 1 CT was associated with overall survival. Results: Of 371 eligible patients (median age 63.9 years, 47% male, 94% non-squamous histology, 30% never-smokers, 58% ECOG 0-1, 20% EGFR positive and 8% ALK positive, and 27% brain metastases), 118 (32%) enrolled in ≥ 1 CT. Of CT enrollees: 19% enrolled in > 1 CT, 89% in phase I/II trials, 15% in phase III trials, 26% in randomized trials, and 51% in trials of drugs later approved by the FDA. Median survival in CT enrollees was 838 days (95% CI 688, 1,021), as compared to 454 days in non-enrollees (95% CI 378, 511). After adjusting for sex, ECOG score, smoking, histology, EGFR and ALK status, and presence of brain metastases, CT enrollees had a 47% lower risk of death relative to non-enrollees (HR 0.53; 95% CI 0.13, 0.92; P = 0.002). Conclusions: Participation in therapeutic drug trials is associated with longer overall survival in advanced NSCLC. Besides supporting drug development, CT participation may directly benefit NSCLC patients by providing access to promising agents and/or enhanced supportive care.