This open-label, multicenter study will assess the safety, tolerability, and pharmacokinetics of intravenous (IV) dosing of MPDL3280A and oral dosing of Tarceva (erlotinib) administered in combination to patients with non-small cell lung cancer (NSCLC). This study has two stages. In the safety evaluation stage, patients with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI)-treatment-naive, advanced NSCLC will be given Tarceva at a starting daily dose of 150 mg for 28 consecutive days during Cycle 1 and for 21-day cycles thereafter. The starting dose of MPDL3280A will be 1200 mg, administered every 3 weeks starting on Day 8 of Cycle 1. If the starting regimen is not tolerated, alternative doses and/or schedules of Tarceva and MPDL3280A may be tested. In the expansion stage, patients with previously untreated, EGFR mutation-positive, advanced NSCLC will be treated with a potential recommended phase 2 dose and schedule based on the treatment established in safety evaluation stage. For both stages, continuation of treatment beyond Cycle 1 will be at the discretion of the treating investigator. In the absence of unacceptable toxicity or disease progression, treatment with MPDL3280A may be continued for a maximum of 17 cycles (or 12 months, whichever occurs first). Tarceva may be continued until disease progression in the absence of unacceptable toxicity. Time on study is expected to be approximately 15 months.