To facilitate access to care and to ensure adherence to diagnostic follow-up of positive breast cancer screening or prescribed treatment for confirmed cancer, community volunteers were used as patient navigators (PNs) for a population of low-income, medically under-served women, primarily African Americans. Partnerships were established with local healthcare facilities, residents from the targeted areas were hired as county coordinators, and community volunteers were trained to serve as PNs. Patients who had a suspicious mammogram or confirmed diagnosis of breast cancer were recruited from 23 Alabama counties. For these patients, barriers to diagnostic follow-up or treatment were identified by PNs, who assisted in overcoming these barriers by referring patients to appropriate treatment facilities, guiding them through the healthcare system, and providing the necessary logistical, social, or emotional support. With this intervention, patients kept 93% of their appointments. Thus, for medically under-served patients with breast cancer or a suspicious mammogram, intervention by a network of community volunteers serving as PNs improves adherence to follow-up diagnostic procedures and treatment. PNs can help close the gap between development and delivery of cancer treatments to those who are medically underserved.