Lung cancers are immunogenic tumors that manage to evade the immune system by exploiting checkpoint pathways that render effector T cells anergic. Inhibition of these checkpoints can restore and invigorate endogenous antitumor T-cell responses. The immunotherapeutic approach of checkpoint inhibition has become an important treatment option for patients with advanced non-small cell lung cancer, playing a role that will continue to evolve over the coming years. The programmed death 1 inhibitors nivolumab and pembrolizumab have both been shown to induce durable responses and improve survival in a subset of patients with platinum-refractory metastatic non-small cell lung cancer. Nivolumab has recently earned Food and Drug Administration approval for progressive squamous cell lung cancer. Optimization and validation of a pretreatment biomarker to predict response is a key area of ongoing research. Combination therapy is now being investigated in an effort to improve response rates.