OBJECTIVE: Advanced stage at diagnosis for breast cancer is associated with lower socio-economic status (SES). We explored what factors in the patient interval (time from noticing a bodily change to first consultation with a health care professional) may contribute to this inequality. DESIGN: Qualitative comparative study. METHODS: Semi-structured interviews with a sample of women (≥47 years) from higher (n = 15) and lower (n = 15) educational backgrounds, who had experienced at least one potential breast cancer symptom. Half the participants (n = 15) had sought medical help, half had not (n = 15). Without making breast cancer explicit, we elicited women's sense-making around their symptoms and help-seeking decisions. RESULTS: Containment of symptoms and confidence in acting upon symptoms emerged as two broad themes that differentiated lower and higher educational groups. Women from lower educational backgrounds tended to attribute their breast symptoms to trivial factors and were reticent in using the word 'cancer'. Despite 'knowing' that symptoms could be related to cancer, women with lower education invoked lack of medical knowledge - 'I am not a doctor' - to express uncertainty about interpreting symptoms and accessing help. Women with higher education were confident about interpreting symptoms, seeking information online, and seeking medical help. CONCLUSIONS: Our findings suggest that knowledge of breast cancer alone may not explain socio-economic differences in how women respond to breast cancer symptoms as women with lower education had 'reasons' not to react. Research is needed on how to overcome a wider spectrum of psycho-social factors to reduce future inequality. STATEMENT OF CONTRIBUTION What is already known on this subject? Seven of ten breast cancers in the UK are diagnosed after people contact their doctor with symptoms. Women from lower socio-economic backgrounds are more likely to be diagnosed with advanced disease. There is little evidence related to potential drivers of this SES inequality. What does this study add? We qualitatively explored socio-economic (SES) differences in help-seeking for breast symptoms. Women with higher education were more confident about interpreting symptoms and navigating health care. Women with lower education were more reluctant to seek help due to fear of cancer.