Despite being the basis of one of the most effective interventions in lung cancer, little is known about the patterns of epidermal growth factor receptor (EGFR) mutation testing in the general population. We assessed the frequencies and determinants of EGFR testing and erlotinib treatment among a population-based sample. A random sample (n = 1,358) of patients diagnosed in 2010 with histologically-confirmed NSCLC, as reported to the Surveillance Epidemiology and End Results (SEER) program, had their medical records abstracted and treating physicians queried. Logistic regression was used to identify factors associated with EGFR testing and erlotinib treatment. Survival was examined using Cox proportional hazards regression. The frequency of EGFR testing was 16.8% overall and 22.6% for stage IV adenocarcinoma patients. Given an EGFR mutation, 33.6% of all patients and 48.3% of stage IV patients received erlotinib. Among stage IV patients, increased age, Medicaid/no/unknown insurance status, death within 2 months of diagnosis and comorbidity were inversely associated with EGFR testing; erlotinib treatment was less likely among smokers and patients with non-adenocarcinomas. EGFR-mutation was associated with improved survival, albeit only among stage IV adenocarcinomas. Less than a quarter of NSCLC patients diagnosed in 2010 received EGFR testing and less than half of the patients with EGFR-mutant stage IV tumors received erlotinib. Significant disparities were observed in EGFR mutation testing by health insurance status, comorbidity and age. A national strategy is imperative to ensure that resources and processes are in place to efficiently implement molecular testing of cancer.