In this trial we adopted the approach of using both induction and concurrent chemotherapy together with Thoracic Radiation Therapy (TRT) planned conformally to a tumor dose of 74 Gy. Substitution of gemcitabine for paclitaxel in the induction chemotherapy allowed us to evaluate the impact of RRM1 expression on the activity of this agent. The expression of Ribonucleotide Reductase, M1 Subunit (RRM1) was evaluated prior to initiation of therapy, following induction chemotherapy but prior to concurrent chemoradiation, and following completion of all therapy by CT-guided core needle biopsies. This is a single institution phase II clinical trial, of induction treatment with gemcitabine and carboplatin followed by concurrent chemoradiation using paclitaxel and carboplatin and daily thoracic radiation to a total dose of 74 Gy for patients with unresectable Stage IIIA and IIIB NSCLC. The specific clinical objectives of this study are as follows: To determine the response rate (both CT scan and PET scan assessment) to two cycles of induction chemotherapy with gemcitabine and carboplatin; To determine the response rate (both CT scan and PET scan assessment) to concurrent thoracic radiation and weekly paclitaxel and carboplatin; To evaluate the patterns of local and distant failure for patients treated with induction chemotherapy followed by concurrent chemoradiation according to this regimen; To estimate the median, 1 year, and overall survival; To assess acute and long term toxicities of treatment.