The present study evaluated the use of the Millon Behavioral Health Inventory (MBHI) in predicting response to a behavioral treatment program for headache reduction. A secondary goal was to also assess whether the MBHI could significantly differentiate among headache patients, patients with other types of chronic pain, and normal subjects. Twenty-three chronic headache sufferers were administered a behavioral treatment program which consisted of 16, one-hour weekly sessions. During the course of the treatment program, subjects were requested to keep daily records of four measures which later served as the treatment-outcome indices: (1) daily number of headaches, (2) duration of headaches, (3) intensity of headaches, (4) medications taken. Results demonstrated that a number of MBHI scales significantly predicted response to treatment. Also, it was found that the MBHI significantly differentiated the chronic headache patients from the normal controls and patients with other forms of chronic pain.