African American women have a lower rate of regular mammography screening, resulting in higher incidence of advanced-stage breast cancer at diagnosis and a lower 5-year survival rate as compared with white women. Researchers have demonstrated that several health beliefs relate to mammography screening in African American women, but little attention has been paid to the importance of religiousness. Although some authors have attempted to determine a link between religiousness and health, we lack a valid and reliable instrument to measure religiousness that can be found in the context of health behaviors. The purpose of this article is to describe the development and psychometric testing of the Wagle Health-Specific Religiousness (WHSR) scale, an instrument used to measure religious beliefs and the influence of those beliefs on mammography screening for African American women. A sample of 344 low-income African American women who were nonadherent to mammography at accrual participating in a randomized trial completed the WHSR. Data from this trial were used to determine the validity and reliability of the WHSR. The 19-item WHSR scale had a Cronbach α of. 94. Construct validity was supported via factor analysis and analysis of theoretical relationships. Although further testing is warranted, this analysis indicates that the concept of religiousness is an important component of mammography behavior in African American women.