Immune checkpoint inhibitors, specifically PD-1-directed agents, have changed the treatment paradigm of non-small cell lung cancer (NSCLC) and are being actively evaluated in patients with small cell lung cancer. After initial studies demonstrated survival advantage with these agents in patients with recurrent NSCLC, these agents now have demonstrated survival advantage in some patients with early-stage NSCLC. Further evaluation of these agents in combination with chemotherapy regimens and other checkpoint inhibitors is ongoing. Recent data suggest that addition of these agents to chemotherapy may improve survival compared with chemotherapy alone. Promising results have also been observed in patients with recurrent small cell lung cancer. Ongoing studies will define the role of these agents in the management of patients with small cell lung cancer. Tumor PD-L1 assessment has become standard of care since use of frontline pembrolizumab in patients with advanced NSCLC is based on tumor PD-L1 expression. Other biomarkers are being actively evaluated to identify the patients most likely to benefit from these agents. Unique adverse effects are observed with the use of immune checkpoint inhibitors. Knowledge of the adverse effects and their management is crucial in treating patients with lung cancer using immune checkpoint inhibitors.