Diagnostic imaging plays a central role in the evaluation and management of patients with lung cancer. This ranges from screening high-risk current or former smokers with low-dose CT, interpreting imaging studies performed for chest or systemic symptoms showing suspicious abnormalities, the incidental detection of findings in asymptomatic patients that are concerning for lung cancer, providing a clinical stage of disease to help direct diagnostic biopsy, guiding disease management, and assessing the patient’s response to or detecting the complications of treatment. This chapter begins with a brief review of the epidemiology, risk factors, and pathology of lung cancer, and describes the most common presenting symptoms and their correlative imaging findings that tend to differ based on tumor histology. Common radiographic and CT findings associated with lung cancer are detailed, followed by a description of the TNM classification system used to determine the clinical stage of disease that helps direct diagnostic biopsy and determine appropriate treatment options and disease prognosis. The recent ninth edition of the TNM system and the changes to the nodal and metastatic disease characterization are highlighted. The staging groups for lung cancer that range from stage I (solitary pulmonary nodules) to stage IV (metastatic disease) are summarized.