Introduction:In India, mortality rate in breast cancer is high because more than half are diagnosed late at locally advanced or metastatic stages. This might be due to presentation delay (recognition of symptoms to first provider consultation) and treatment delay (first provider consultation to initiation of treatment), together known as overall delay. We aimed to estimate the overall delay in diagnosis and treatment in breast cancer and the associated factors, describe pathway of care and explore the reasons for delay from a patients' and providers' perspective. Methods: Explanatory sequential mixed-methods study with a quantitative component (retrospective cohort study including breast cancer patients registered at Dr. Borooah Cancer Institute (BBCI), Guwahati during February-June 2019) followed by descriptive qualitative component (in-depth interviews with 15 patients and 10 care providers). Results: Of 269 breast cancer patients, median (Inter Quartile Range) overall delay was 203 (110-401) days, presentation delay was 35 (10-112) days and treatment delay was 130 (75-258) days. Majority of patients approached private sector (190, 70.6%) as the first care provider. Nearly half of all patients (136, 50.6%) visited one health care provider before reaching the BBCI and another one-third (90, 33.5%) visited two providers. Reasons for presentation delay were misconception about the disease, perceived stigma, fear and denial of cancer, attribution of symptoms to trivial conditions, family responsibilities and embarrassment of breast examination by a male doctor. Treatment delay was due to initial visit to, misclassification of disease severity, dissatisfaction with care at public facilities, poor accessibility and affordability, fear of treatment and its side effects. Conclusion: Treatment delay was the major contributor to overall delay. Private providers need to be sensitized and trained in screening of breast cancer and referral of suspected cases of cancer. More awareness is needed about warning symptoms of breast cancer and misconceptions regarding the disease.