The headache-specific locus of control scale: adaptation to recurrent headaches. This paper describes the development, psychometric properties, and construct and incremental validity of a Headache-Specific Locus of Control Scale (HSLC). The HSLC is a 33 item scale designed specifically for recurrent headache sufferers. It assesses the individual's perceptions that headache problems and headache relief are determined primarily by: the individual's behavior (Internal factors), Health Care Professionals, or Chance factors. The psychometric properties of the HSLC were satisfactory. Among our findings were that: (1) the belief that headache problems and relief are determined by chance factors was associated with higher levels of depression, physical complaints, reliance on maladaptive pain coping strategies (p less than .001), and greater headache-related disability (p less than .01); (2) the belief that headache problems and relief are influenced primarily by the ministrations of health care professionals was associated with higher levels of medication use (p less than .01) and preference for medical treatment (p less than .001); and (3) the belief that headache problems are determined by the individual's responses and behaviors was associated with a preference for self-regulation treatment (p less than .01). These findings suggest adaptation to headache problems is influenced not only by the frequency and severity of the headache episodes, but by locus of control beliefs. The assessment of locus of control beliefs may provide useful information not typically obtained from standard medical evaluations. 