For more information regarding Bristol-Myers Squibb Clinical Trial participation, please visit www.BMSStudyConnect.com Inclusion Criteria: - Histologically confirmed metastatic or recurrent squamous cell carcinoma of the head and neck (oral cavity, oropharynx, hypopharynx & larynx) that is not amenable to curative therapy. - No prior systemic cancer therapy for recurrent or metastatic disease (except if chemotherapy was part of multimodal treatment completed 6 months prior to enrolment). - Measurable disease detected by imaging exam (CT or MRI). - Have tumor tissue for PD L1 expression testing, and for oropharyngeal cancer have results from testing of HPV p16 status. Exclusion Criteria: - Metastatic or recurrent carcinoma of the nasopharynx, squamous cell carcinoma of unknown primary, squamous cell carcinoma originating from skin and salivary glands or non squamous histologies (eg. mucosal melanoma). - No prior treatment with anti PD1, anti PD L1, anti CTLA 4 antibody or any other antibody or drugs targeting T cell costimulation or checkpoint pathways, or cetuximab or EGFR inhibitors in any treatment setting. - Participants with certain diseases such as active autoimmune disease, type I diabetes, hypothyroidism that needs hormone replacement, active infection, psychiatric disorder. - Inadequate hematologic, renal or hepatic function. Other protocol defined inclusion/exclusion criteria could apply