The elimination of cancer disparities is critically important for lessening the burden of breast cancer (BC). Patient navigator programs (PNPs) have been shown to improve rates of BC screening in underserved communities, but there is a dearth of evidence regarding their benefits after the actual diagnosis of BC. We retrospectively examined sociodemographic characteristics, disease characteristics, and concordance to quality measures (QMs) of BC care among women participating in a PNP that services disadvantaged minority communities in the greater Boston area. Of the 186 PNP patients diagnosed with BC in 2001-2011 in three neighborhood community health centers, treatment data was available for 158 (85%) and race and disease stage information was available for 149 (80%). Regarding stage, 25% were diagnosed with in situ cancer, 32% had stage 1, 25% had stage 2, 13% had stage 3, and 5% had stage 4 BC. Guideline-indicated care was received by 70 of 74 patients (95%) for the hormonal therapy QM, 15 of 17 (88%) patients for the chemotherapy QM, and 65 of 71 (92%) patients for the radiation QM, all similar to published concordance rates at elite National Comprehensive Cancer Network institutions. These findings suggest that PNPs may facilitate evidence-based quality care for vulnerable populations. Future research should prospectively analyze quality metrics to assess measures to improve the process and outcomes of patient navigation in diverse underserved settings, compared with control non-navigated populations.