Abstract On October 15, 2021, the FDA approved atezolizumab as adjuvant therapy in patients with stage II to IIIA non–small cell lung cancer (NSCLC) whose tumors have programmed cell death ligand 1 (PD-L1) expression on ≥1% of tumor cells (TC), as detected by an FDA-approved test. The approval was based on results from the IMpower010 trial, in which 1,005 patients with NSCLC who had completed tumor resection and cisplatin-based adjuvant chemotherapy were randomly assigned 1:1 to receive atezolizumab for 16 cycles or best supportive care. The primary endpoint of disease-free survival (DFS) as assessed by investigator was tested hierarchically in the following analysis populations: stage II–IIIA NSCLC with PD-L1 expression on ≥1% of TCs (PD-L1 ≥ 1% TC); all randomly assigned patients with stage II–IIIA NSCLC; and the intent-to-treat population comprising all randomly assigned patients. At the prespecified interim DFS analysis, IMpower010 demonstrated a statistically significant and clinically meaningful improvement in DFS in the stage II–IIIA PD-L1 ≥ 1% TC analysis population, with an HR of 0.66 (95% confidence interval, 0.50–0.88; P = 0.004) favoring the atezolizumab arm. The safety profile of atezolizumab was generally consistent with known toxicities of anti–PD-(L) antibodies. The VENTANA PD-L1 (SP263) Assay (Ventana Medical Systems, Inc.) was contemporaneously approved as a companion diagnostic device to select patients with NSCLC who are PD-L1 ≥ 1% TC for adjuvant treatment with atezolizumab. Atezolizumab is the first immune checkpoint inhibitor approved by FDA for the adjuvant treatment of NSCLC.