This randomized, Phase III, double-blind, placebo-controlled study will evaluate the safety and efficacy of MetMAb (onartuzumab) in combination with Tarceva (erlotinib) compared with treatment with Tarceva alone in patients with incurable Met-positive non-small cell lung cancer (NSCLC). Patients will be randomized in a 2:1 ratio to receive either MetMAb + Tarceva or placebo + Tarceva. Tarceva (150 mg) will be given orally once daily, and MetMAb (15 mg/kg) will be given intravenously every 3 weeks. Treatment will continue until disease progression, unacceptable toxicity, a decision to discontinue, or death occurs. Total study length is expected to be around 36 months.