A sense of competence or self-efficacy is associated with many positive outcomes, particularly in the area of health behavior. A measure of a sense of competence in the domain of health behavior has not been developed. Most measures are either general measures of a general sense of self-efficacy or are very specific to a particular health behavior. The Perceived Health Competence Scale (PHCS), a domain-specific measure of the degree to which an individual feels capable of effectively managing his or her health outcomes, was developed to provide a measure of perceived competence at an intermediate level of specificity. Five studies using three different types of samples (students, adults and persons with a chronic illness) provide evidence for the reliability and validity of the PHCS. The eight items of the PHCS combine both outcome and behavioral expectancies. Results from the five studies indicate that the scale has good internal consistency and test-retest reliability. The construct validity of the scale is demonstrated through the support obtained for substantive hypotheses regarding the correlates of perceived health competence, such as health behavior intentions, general sense of competence and health locus of control.