The new international classification of headache disorders (IHCD-2) contains precise diagnostic criteria for headache disorders, but it is very difficult to read. The book, edited by the chairman of the classification committee, provides an invaluable insight for all those who diagnoseheadache in their daily practice. This book follows the International Headache Classification, but expands on it by discussing the background of the various diagnoses, the pitfalls and the practical problems in interpretation, and thus provides a more comprehensive source for those diagnosingheadache disorders. It discusses diagnostic instruments such as headache diaries, headache calendars, and structured interviews. It also focuses on weak points in the headache classification where solid data is missing, and personal experience plays a greater role. Finally, it provides an insightfor future descriptive research. A whole catalogue of research ideas are presented which can be realized in any clinical setting where a large number of headache patients are being treated.