The 8th edition of Wolff's Headache and Other Head Pain remains the definitive reference text in the field. Our knowledge and understanding of headache and its management have changed significantly in the twenty-first century. A new international headache classification has been adopted; headache pathophysiology and genetics have advanced; and epidemiologic studies have burgeoned. We have greater insights into the diagnosis and treatment of the secondary headaches. New treatments are available for primary headache disorders, including migraine, cluster, and chronic daily headache, and our understanding and knowledge are increasing by means of ongoing trials. The 8th edition encompasses all of this new material, with all chapters updated and many new authors added.