Information on 23,567 Non-Hispanic White, 2,539 Black, and 2,380 Hispanic breast cancer cases diagnosed between 1977 and 1985 was used to evaluate the risk of late stage diagnosis and long duration of symptoms prior to diagnosis in relation to ethnicity, socioeconomic status, age and year of diagnosis. All data were collected by the University of Southern California Cancer Surveillance Program, the comprehensive population-based incidence registry of Los Angeles County. The results indicate that lower socioeconomic status, Black or Hispanic ethnicity, younger age, and earlier year of diagnosis are risk factors for late stage diagnosis and long duration of symptoms. The effect of ethnicity was not explained by lower SES levels among Black or Hispanic women. After controlling for duration of symptoms, race and SES remained significantly predictive of more advanced stage. More recent diagnosis across the 9 year time frame was not associated with improved stage for those of low SES. These results suggest that increased efforts are needed to reach low SES and Black and Hispanic women with campaigns to improve the stage at which breast cancer is detected.