Over the centuries, the breast cancer literature has contained numerous references to the role of psychological factors in the etiology of the disease. Theories and research findings pertaining to this work are reviewed, with a focus on twentieth century work. The specific hypotheses examined in each historic period can be seen in the context of views held about women in society. Epidemiologic features of breast cancer, particularly certain reproductive behaviors, are associated with specific lifestyles, and these features lend themselves to the investigation of the role of personality in the etiology of the disease. In the eighteenth and 19th centuries, clinicians wrote of the role of depression, grief and anxiety in the etiology of breast cancer. Hard work, which women were not supposed to engage in, resulted in breast tumors. The rise of interest in psychodynamic theories in the twentieth century resulted in a proliferation of investigations demonstrating the association between sexual repression or ambivalence about the female role and breast cancer. The language of psychoanalysis was used throughout society. Single women, at increased risk of breast cancer, were seen as suffering from unconscious rejection of their femininity. Although the study designs used to investigate this association were inadequate and the findings equivocal, belief in this association has continued. More recent work in this field has focussed on the role of repressed anger, reflecting a societal preoccupation with constraints on self-expression. Hypotheses regarding the psychological etiology of breast cancer can be examined in the social context in which they evolve and tend to reflect views of women rather than truths derived from research data.