A Study of Atezolizumab as Adjuvant Therapy in Participants With Renal Cell Carcinoma (RCC) at High Risk of Developing Metastasis Following Nephrectomy

Inclusion Criteria:

* ECOG performance status of less than or equal to (\</=) 1
* Pathologically confirmed RCC with a component of either clear cell histology or sarcomatoid histology that has not been previously treated in the adjuvant or neoadjuvant setting and classified as being at high risk of RCC recurrence
* Radical or partial nephrectomy with lymphadenectomy in select participants
* Absence of residual disease and absence of metastasis, as confirmed by a negative baseline computed tomography (CT) of the pelvis, abdomen, and chest no more than 4 weeks prior to randomization. Confirmation of disease-free status will be assessed by an independent central radiologic review of imaging data.
* Absence of brain metastasis, as confirmed by a negative CT with contrast or magnetic resonance imaging (MRI) scan of the brain, no more than 4 weeks prior to randomization. Applicable only to metastasectomy participants
* Full recovery from nephrectomy or metastasectomy within 12 weeks from randomization following surgery

Exclusion Criteria:

* Bilateral synchronous tumors with inheritable forms of RCC including von Hippel-Lindau
* Any approved anti-cancer therapy, including chemotherapy or hormonal therapy, within 3 weeks prior to initiation of study treatment
* Treatment with any other investigational agent or participation in another clinical study with therapeutic intent within 28 days or five half-lives of the investigational agent, whichever is longer, prior to enrollment
* Malignancies other than RCC within 5 years prior to Cycle 1, Day 1
* History of autoimmune disease
* Participants with prior allogeneic stem cell or solid organ transplantation
* History of idiopathic pulmonary fibrosis (including pneumonitis), drug-induced pneumonitis, organizing pneumonia (i.e., bronchiolitis obliterans, cryptogenic organizing pneumonia), or evidence of active pneumonitis on screening chest CT scan
* Positive test for HIV
* Participants with active hepatitis B or hepatitis C
* Active tuberculosis
* Severe infections within 4 weeks prior to randomization including but not limited to hospitalization for complications of infection, bacteremia, or severe pneumonia
* Major surgical procedure within 4 weeks prior to randomization or anticipation of need for a major surgical procedure during the course of the study other than for diagnosis
* Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1
* Any other diseases, metabolic dysfunction, physical examination finding, or clinical laboratory finding giving reasonable suspicion of a disease or condition that contraindicates the use of an investigational drug or that may affect the interpretation of the results or render the participant at high risk from treatment complications
* Prior treatment with cluster of differentiation (CD)137 agonists, anti-cytotoxic T-lymphocyte-associated protein-4 (anti-CTLA-4), anti-programmed death-1 (anti-PD-1), or anti-programmed death-ligand 1 (anti-PD-L1) therapeutic antibody or pathway-targeting agents
* Treatment with systemic immunostimulatory agents (including but not limited to interferons or interleukin-2) within 6 weeks or five half-lives of the drug, whichever is shorter, prior to randomization
* Treatment with systemic immunosuppressive medications (including but not limited to corticosteroids, cyclophosphamide, azathioprine, methotrexate, thalidomide, and anti-tumor necrosis factor agents) within 2 weeks prior to randomization or anticipated need for systemic immunosuppressive medications during the study