Background: Breast cancer care requires coordination between multiple diagnostic and treatment modalities. Disparities such as age, race/ethnicity, and socioeconomic status are associated with delays in care. This study investigates whether primary language is associated with delays in breast cancer diagnosis and treatment before and through radiotherapy (RT). Patients and Methods: This study was an institutional retrospective matched-cohort analysis of women treated with breast RT over 2 years. A total of 65 non–English-speaking (NES) patients were matched with 195 English-speaking (ES) patients according to stage, age, and chemotherapy delivery. Key time intervals along the breast cancer care path from initial findings through RT were recorded. Data were analyzed in a mixed model with matching as the random effect. The impact of race and insurance status was analyzed in addition to language. Results: Significant delays were found for NES patients, which varied by race. NES Latina patients experienced the longest delay, with a mean total care-path time of 13.53 months (from initial findings to end of RT) versus 8.18 months for all ES patients (P<.0001). Specifically, their mean total care-path time was 5.97 months longer than that of ES Latina patients (P=.001) and 5.80 months longer than that of ES White patients (P<.0001). In addition, NES Latina patients had a significantly longer total care-path time than NES patients of other races/ethnicities (P=.001). Delays were specifically seen between initial clinical or radiographic findings and diagnostic mammogram (P=.001) and between biopsy and resection (P=.044). Beyond language, race/ethnicity was itself associated with delays between resection and start of RT (P=.032) and between start and end of RT (P=.022). Conclusions: Language is associated with pre-RT delays in breast cancer care, especially for NES Latina patients. Delays are most pronounced before diagnostic mammograms, but they also exist before resection and RT. Future work should target NES patients to assist their progress along the care path.