Purpose: To determine the role of adjuvant chemotherapy and radiation therapy in patients with completely resected stage IA-IIIA non–small-cell lung cancer (NSCLC). Methods: The Cancer Care Ontario Program in Evidence-Based Care and the American Society of Clinical Oncology convened a Joint Expert Panel in August 2006 to review the evidence and draft recommendations for these therapies. Results: Available data support the use of adjuvant cisplatin-based chemotherapy in completely resected NSCLC; however, the strength of the data and consequent recommendations vary by disease stage. Adjuvant radiation therapy appears detrimental to survival in stages IB and II, with a possible modest benefit in stage IIIA. Conclusion: Adjuvant cisplatin-based chemotherapy is recommended for routine use in patients with stages IIA, IIB, and IIIA disease. Although there has been a statistically significant overall survival benefit seen in several randomized clinical trials (RCTs) enrolling a range of people with completely resected NSCLC, results of subset analyses for patient populations with stage IB disease were not significant, and adjuvant chemotherapy in stage IB disease is not currently recommended for routine use. To date, very few patients with stage IA NSCLC have been enrolled onto RCTs of adjuvant therapy; adjuvant chemotherapy is not recommended in these cases. Evidence from RCTs demonstrates a survival detriment for adjuvant radiotherapy with limited evidence for a reduction in local recurrence. Adjuvant radiation therapy appears detrimental to survival in stage IB and II, and may possibly confer a modest benefit in stage IIIA.