In Stage 3 NSCLC, chemotherapy is not merely a standalone “drug course”; it is a core component of multimodal care. In resectable cases, neoadjuvant (pre-surgery) or adjuvant (post-surgery) chemotherapy targets microscopic disease and helps reduce recurrence risk. In unresectable Stage 3, concurrent chemoradiation is a standard approach that improves local control and survival compared with sequential strategies in suitable patients. For eligible individuals, consolidation immunotherapy after chemoradiation can further strengthen outcomes. Whether chemotherapy “works” depends on Stage 3 subgroup, performance status, comorbidities, and tumor biology. The optimal plan is best defined through multidisciplinary decision-making involving medical oncology, radiation oncology, and thoracic surgery.