Headache is a common complaint that affects the majority of the population at some point in their lives. The underlying pathological bases for headache symptoms are many, diverse, and often difficult to distinguish. Classification of headache is principally based on the evaluation of headache symptoms as well as clinical testing. Although manual therapy has been advocated to treat a variety of different forms of headache, the current evidence only supports treatment for cervicogenic headache (CGH). This form of headache can be identified from migraine and other headache forms by a comprehensive musculoskeletal examination. Examination and subsequent diagnosis is essential not only to identify patients with headache where manual therapy is appropriate but also to form a basis for selection of the most appropriate treatment for the identified condition. The purpose of this paper is to outline, in clinical terms, the classification of headache, so that the clinician can readily identify those patients with headache suited to manual therapy.