This randomized, multicenter, double-blind, placebo-controlled study will evaluate the efficacy and safety of onartuzumab (MetMAb) in combination with Tarceva (erlotinib) in participants with incurable non-small cell lung cancer identified to be Met diagnostic-positive. Participants will be randomized to receive either onartuzumab (MetMAb) or placebo in combination with erlotinib. Anticipated time on study treatment is until disease progression or unacceptable toxicity occurs.

Inclusion Criteria:

• Adult participants, greater than or equal to (>/=) 18 years of age
• Eastern Cooperative Oncology Group (ECOG) performance status 0-1
• Histologically or cytologically confirmed incurable Stage IIIb/IV NSCLC tumor
• Met diagnostic-positive status tested by immunohistochemistry (IHC)
• Results of endothelial growth factor receptor (EGFR)-activating mutation testing
• Radiographic evidence of disease
• Prior treatment with at least one platinum-based line of treatment (for stage IIIb/IV) and no more than one additional line of chemotherapy treatment; the last dose of chemotherapy must have been administered >/= 21 days prior to Day 1
• availability of tissue sample for diagnostic testing is required

Exclusion Criteria:

• More than 30 days of exposure to an investigational or marketed agent that can act by EGFR inhibition, or a known EGFR-related toxicity resulting in dose modifications (EGFR inhibitors including but not limited to gefitinib, erlotinib and cetuximab)
• Brain metastases or spinal cord compression not definitively treated with surgery and/or radiation, or previously treated central nervous system (CNS) metastases or spinal cord compression without evidence of stable disease for >/= 14 days
• History of another malignancy in the previous 3 years, unless cured by surgery alone and continuously disease free for at least 3 years; participants with prior history of non-invasive cancers are eligible
• Inadequate hematological, biochemical or organ function
• Significant history of cardiac disease
• Serious active infection at time of randomization or other serious underlying medical conditions that would impair the ability of the participant to receive protocol treatment
• Any inflammatory changes of the surface of the eye
• Clinically significant gastro-intestinal disease, including uncontrolled inflammatory gastro-intestinal diseases
• Pregnant or lactating women
• Positive for human immunodefinciency (HIV) infection