A Study of Atezolizumab in Participants With Programmed Death - Ligand 1 (PD-L1) Positive Locally Advanced or Metastatic Non-Small Cell Lung Cancer

Inclusion Criteria: * Adult participants greater than or equal to 18 years of age * Locally advanced or metastatic (Stage IIIB, Stage IV, or recurrent) NSCLC * Representative formalin-fixed paraffin-embedded (FFPE) tumor specimens * PD-L1-positive tumor status as determined by an immunohistochemistry (IHC) assay based on PD-L1 expression on tumor infiltrating immune cells and/or tumor cells performed by a central laboratory * Measurable disease, as defined by RECIST version 1.1 * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 Exclusion Criteria: * Any approved anti-cancer therapy, including chemotherapy, or hormonal therapy within 3 weeks prior to initiation of study treatment; the following exception are allowed: Hormone-replacement therapy or oral contraceptives tyrosine-kinase inhibitors (TKIs) approved for treatment of NSCLC discontinued \>7 days prior to Cycle 1, Day 1 * Central nervous system (CNS) disease, including treated brain metastases * Malignancies other than NSCLC within 5 years prior to randomization, with the exception of those with negligible risk of metastases or death and treated with expected curative outcome * History of autoimmune disease * History of idiopathic pulmonary fibrosis (including pneumonia), drug-induced pneumonitis, organizing pneumonia, or evidence of active pneumonitis on screening CT scan. History of radiation pneumonitis in the radiation field (fibrosis) id permitted * Active hepatitis B or hepatitis C * Human Immunodeficiency virus (HIV) positive * Prior treatment with CD137 agonists, anti-CTLA4, anti-PD-1, or anti-PD-L1 therapeutic antibody or pathway-targeting agents