This manuscript is a review of the recently published ACR Appropriateness Criteria Radiologic Management of Thoracic Nodules and Masses. Presented are best practice guidelines for the imaging evaluation and biopsy recommendations for pulmonary nodules, mediastinal masses, and pleural abnormalities. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.