For more information regarding BMS clinical trial participation, please visit www.BMSStudyConnect.com Inclusion Criteria: - ECOG Status: PS 0-1 & PS 2 - Subjects with histologically or cytologically-documented SqNSCLC - Subjects must have experienced disease progression or recurrence during or after one prior platinum doublet-based chemotherapy regimen - Subjects must have evaluable disease by CT or MRI per RECIST 1.1 criteria - Subjects with treated or asymptomatic CNS metastases - Prior palliative radiotherapy must have been completed at least 14 days prior to study drug administration - Prior lines of antineoplastic therapy, including hemotherapy, hormonal therapy, immunotherapy, surgical resection of lesions, non-palliative radiation therapy, or standard or investigational agents for treatment of NSCLC, must be completed 28 days prior to the first dose of nivolumab - Males and Females, ages 18 or older Exclusion Criteria: - Subjects with untreated, symptomatic CNS metastases - Subjects with carcinomatous meningitis - Subjects with active, known or suspected autoimmune disease. - Subjects who received prior therapy with anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or anti-CTLA-4 antibody (including ipilimumab or any other antibody or drug specifically targeting T-cell costimulation or checkpoint pathways) or who have previously taken part in a randomized BMS clinical trial for nivolumab or ipilimumab.