Two quantitative measures for Waters' tension-type headache and migraine severity continuum are proposed. To ensure face validity, symptoms and precipitants of this disorder were complied from the literature as a basis for the Auckland Migraine and Headache Inventory. This inventory was completed by 84 participants (mean age +/- SD, 26.0 +/- 9.7 years; range, 18 to 59 years) who complied with the criteria of the International Headache Society for migraine or tension-type headache. The migraine headache index and the number of precipitants were derived from the Auckland Migraine and Headache Inventory. These scores yielded significant internal reliability (r = .77 and .84), test-retest reliability (r = .86 and .74), and concurrent validity (r = .57) coefficients. The data, therefore, support the notion that the migraine headache index and the number of precipitants are reliable and valid indices of tension-type headache and migraine severity, suitable for participant selection and assessment of treatment. This study offers support for Waters' suggestion that tension-type headache and migraine are extremes of a severity continuum.