Patient delay in seeking help for breast cancer symptoms and provider delay in treating those symptoms combine to decrease a woman's potential for breast cancer survival. This paper reviews the literature on patient and provider delay published since 1975. Meta-analysis of 12 studies using common definitions of patient delay estimates that 34% of women with breast cancer symptoms delay help seeking for 3 or more months. Provider delay appears to be both under researched and underestimated. This review identifies the factors that have been advanced as contributing to patient and provider delay, evaluating the support for each of these reported findings. Theory-based hypotheses emerging from the reviewed studies highlight foci for future investigations.