A new scale for the measurement of insomnia, the Bergen Insomnia Scale, was constructed on the basis of current formal and clinical diagnostic criteria for insomnia. There are six items, of which the first three pertain to sleep onset, maintenance, and early morning wakening insomnia, respectively. The last three items refer to not feeling adequately rested, experiencing daytime impairment, and being dissatisfied with current sleep. This scale was validated in three samples, 320 students, 2645 community persons, and 225 patients. Cronbach alphas in the three samples were .79, .87, and .80, respectively. The 2-wk. test-retest reliability for students was .77. In the student and the patient samples, a two-factor solution was found, nocturnal symptoms and daytime symptoms, but in the community sample, a one-factor solution was found. The Bergen Insomnia Scale discriminated well between the patient sample and the other two. In all three, values of convergent and discriminative validity in relation to other self-report measures were good, as well as in relation to polysomnographic data for patients. It is concluded that the Bergen Insomnia Scale has good psychometric properties. It is one of very few insomnia scales which provide normative data for comparisons and which has been validated against subjective as well as polysomnographic data.