The present guidelines review epidemiology, pathology, presentation, workup, staging, prognostic factors, and treatment options for patients with localized nodal indolent lymphoma, with an emphasis on radiation guidelines, including radiation dose, field design, and radiation techniques. Following a discussion of the current literature and available data for treatment and outcomes of patients with indolent lymphoma, several different example cases are reviewed to help physicians make appropriate treatment decisions. 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) by which the panel rates the appropriateness of imaging and treatment procedures. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.