Small-cell lung cancer (SCLC) is an aggressive form of lung cancer that displays rapid proliferation and early metastatic potential. It accounts for approximately 15% of lung cancers and is strongly associated with tobacco carcinogens. Despite patients' initial response to systemic therapy, the majority develop early resistance and relapse. The outcomes of patients with metastatic SCLC are poor, prompting the need for new therapies. Over the past decade, the treatment landscape for NSCLC (non-small cell lung cancer) has significantly changed with the immergence of novel targeted therapies and immunotherapies. However, inroads of these therapies into SCLC have posed significant challenges due to its molecular and genomic heterogeneity. Despite the challenges of this disease, promising new first-in-class immunomodulatory agents have emerged and are currently undergoing extensive research. Herein, we review the current treatment paradigm of immunotherapy in SCLC and discuss future directions of this evolving field.