This open-label, randomized, multinational, non-comparative, phase IIIb trial with 2 parallel groups will screen about 1400 subjects with stage IIIB non-small cell lung cancer (NSCLC) with pleural effusion or stage IV NSCLC. It is expected that of approximately 1200 (85 percent) subjects who will be included, about 1000 will be Caucasian; about 120 Asian, and the remainder (about 80) will be of other ethnic origin (that is neither Caucasian nor Asian). Approximately 480 (40 percent) subjects are expected to be free of progression at the end of combination treatment with cetuximab and platinum-based chemotherapy. These subjects will be eligible for randomization to intravenous cetuximab maintenance therapy with either 500 milligram per square meter (mg/m^2) every 2 weeks or 250 mg/m^2 weekly (q1w); about 240 subjects are expected per group.