This 2 arm study will evaluate the efficacy, safety, and pharmacokinetics of Tarceva, compared with placebo, following platinum-based chemotherapy in patients with advanced, recurrent, or metastatic NSCLC who have not had disease progression or unacceptable toxicity during chemotherapy. Following 4 cycles of platinum-based chemotherapy, eligible patients will be randomized to receive either Tarceva 150mg po daily, or placebo daily. The anticipated time on study treatment is until disease progression; the target sample size is 500+ individuals.