The administration of chemotherapy at the earliest time (neoadjuvant or induction chemotherapy) following diagnosis in an effort to reduce the risk of disease recurrence. This approach also allows for investigations of molecular parameters that may affect response to chemotherapy and patients' survival. It is our hypothesis that the expression of genes associated with activation, inactivation, and efficacy of the drugs gemcitabine and pemetrexed will predict response to therapy and prognosis. We further hypothesize that the expression of these genes will be altered during chemotherapy, and that the global assessment of tumor proliferation, apoptosis, and genome damage is associated with response to therapy. We propose a phase II study of neoadjuvant chemotherapy with gemcitabine and pemetrexed in patients with resectable NSCLC, specifically correlating molecular and genetic parameters to the primary clinical study endpoint disease response (radiographic CR+PR) and the secondary endpoints complete pathological response at surgery, disease-free survival, and overall survival.