This volume is designed to accomplish 3 specific tasks. First, to help the clinician quickly and accurately identify those patients, based on a brief history and examination, who require investigations to rule out a specific secondary cause for headache. The clinical evaluation should therefore generate a short differential diagnosis and guide the selection of appropriate investigations. The most important secondary causes, especially those that are commonly overlooked, will be briefly discussed, primarily setting out how each disorder presents and when to be suspicious, which tests are appropriate, and the definitive treatment. Second, for those patients with a recurrent primary headache disorder that has not responded to self-administered therapies, an evidence-based approach with specific medication algorithms will be provided. Finally, since 50% of emergency department visits for headache are generated by 'repeat' patients, or so-called frequent fliers, a practical approach to improving outcomes for and reducing repeat visits by these patients will be offered.