This field experiment examined the persuasiveness of matching health messages to individuals' health locus of control beliefs in an effort to promote screening mammography. Women (N = 499) who called the New England regional office of the Cancer Information Service were stratified by their health locus of control and randomly assigned to receive a telephone message and follow-up print materials matched to either an internal or external health locus of control orientation. As expected, women who received information consistent with their health locus of control beliefs generally were more likely to obtain a mammogram 6 and 12 months after the intervention than women who received information that was not consistent with their health locus of control orientation.
