Inclusion Criteria:

- Able to comply with the study protocol, in the investigator's judgment

- Histologically or cytologically documented locally advanced or metastatic urothelial
carcinoma (including renal pelvis, ureters, urinary bladder, and urethra)

- Disease progression during or following treatment with at least one
platinum-containing regimen (e.g., gemcitabine and cisplatin [GC], methotrexate,
vinblastine, doxorubicin, and cisplatin [MVAC], carboplatin and gemcitabine
[CarboGem], etc.) for inoperable locally advanced or metastatic urothelial carcinoma
or disease recurrence

- Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1, or 2

- Life expectancy >/= 12 weeks

- Adequate hematologic and end-organ function, defined by laboratory results obtained
within 14 days prior to the first study treatment

- For women who are not postmenopausal (>/= 12 months of non-therapy-induced
amenorrhea) or surgically sterile (absence of ovaries and/or uterus): agreement to
remain abstinent or use single or combined non-hormonal contraceptive methods that
result in a failure rate of <1% per year during the treatment period and for at
least 90 days after the last dose of study drug

Exclusion Criteria:

- Treatment with any other investigational agent or participation in another clinical
trial with therapeutic intent within 28 days prior to enrollment

- Treatment with chemotherapy 14 days prior to enrollment; however, participants may
be re-screened after the 14-day washout period

- Treatment with radiotherapy 7 days prior to enrollment; however, participants may be
re-screened after the 14-day washout period

- Known primary central nervous system (CNS) malignancy or symptomatic CNS metastases

- Pregnant or lactating, or intending to become pregnant during the study

- Significant cardiovascular disease, such as New York Heart Association cardiac
disease (Class II or greater), myocardial infarction within 3 months prior to
randomization, unstable arrhythmias, or unstable angina

- Severe infections within 4 weeks prior to enrollment, including, but not limited to,
hospitalization for complications of infection, bacteremia, or severe pneumonia

- Received therapeutic oral or intravenous (IV) antibiotics within 14 days prior to
enrollment; however, participants may be re-screened after the 14-day washout period

- Major surgical procedure within 4 weeks prior to enrollment or anticipation of need
for a major surgical procedure during the course of the study other than for
diagnosis

- History of severe allergic, anaphylactic, or other hypersensitivity reactions to
chimeric or humanized antibodies or fusion proteins

- Known hypersensitivity or allergy to biopharmaceuticals produced in Chinese hamster
ovary cells or any component of the atezolizumab formulation

- Any other diseases, metabolic dysfunction, physical examination finding, or clinical
laboratory finding giving reasonable suspicion of disease or a condition that
contraindicates the use of the investigational drug or renders the participant at
high risk for treatment complications

- Participants with active hepatitis B

- Active tuberculosis

- Administration of a live, attenuated vaccine within 4 weeks prior to enrollment or
anticipation that such a live, attenuated vaccine will be required during the study

- Treatment with systemic immunostimulatory agents (including, but not limited to,
interferons or IL-2) within 4 weeks or five half-lives of the drug, whichever is
shorter, prior to enrollment

- Treatment with systemic corticosteroids or other systemic immunosuppressive
medications (including, but not limited to, prednisone, dexamethasone,
cyclophosphamide, azathioprine, methotrexate, thalidomide, and anti-tumor necrosis
factor [anti-TNF] agents) within 2 weeks prior to enrollment or anticipated
requirement for systemic immunosuppressive medications during the trial