Despite strong epidemiologic evidence that screening for breast cancer with mammography and clinical breast examination results in mortality reductions, and the considerable effort to communicate this message to women and health-care providers, most US women are not screened according to recommended guidelines. Recent investigations have focused on trends in use, and factors associated with physicians' and women's knowledge, attitudes, and practices associated with mammography. Even as use of mammography has increased, the literature suggests that a number of significant impediments to participation in routine screening will need to be addressed to achieve high rates of screening among US women according to recommended guidelines.