Non-Hodgkin Lymphomas are always treatable and frequently curable malignancies. However, choosing the most appropriate therapy requires accurate diagnosis and a careful staging evaluation. New patients with non-Hodgkin Lymphoma should have their tumors classified using the World Health Organization classification. The specific choice of therapy is dependent on a careful staging evaluation. Patients with non-Hodgkin Lymphoma are assigned an anatomic stage using the Ann Arbor system. However, patients should also be classified using the International Prognostic Index. New insights into the biology of the lymphomas in the coming years might well improve our ability to evaluate patients and choose therapy.