Low income, older, minority women are at high risk for underutilization of screening mammography. One strategy for increasing utilization is to conduct interventions targeting local and state health departments where a majority of these women seek health care. A prerequisite for conducting effective screening programs is to obtain current and accurate information on baseline screening rates to understand the nature and scope of the problem and to plan appropriate intervention strategies. The sample consisted of 3240 women who were 50+ years of age from 2 hospitals and 2 comprehensive health centers operated by the Los Angeles County Department of Health Services. Reviews of medical records indicated that only 21% of the sample had received a mammogram in the 12 months prior to the clinic visit on which they were sampled and 23% of the sample received a mammogram in the following 9 months. Approximately 5% of the total sample received a repeat mammogram in the 21-month period over which they were tracked. Prospective independent predictors of screening were age, number of visits to primary care clinics, number of visits to specialty care clinics, and history of breast abnormalities. The results underscore the importance of implementing programs to increase mammography implementing programs to increase mammography screening within public facilities serving low income multiethnic women. An important finding is that a large number of older women are seen in specialty clinics, which represents an untapped resource for increasing screening in this population. Innovative interventions targeting such specialty clinics could substantially contribute to increasing screening rates. A comprehensive approach targeting system, physician, and patient barriers is recommended.