The association between diet and breast cancer risk has been investigated extensively and has led to some recommendations for prevention. Research suggests that maintaining a healthy weight may reduce the risk for breast cancer after menopause. Additionally, alcohol increases the risk for breast cancer even at moderate levels of intake, and women who drink alcohol also should take sufficient folate, which can mitigate this excess risk. Interesting questions for future research include the role of soy products, red meat, energy balance, and vitamin D, with particular attention to timing of exposure in early life. Breast cancer is a heterogeneous disease, and dietary factors may differentially affect certain breast cancer subtypes; future studies should therefore attempt to characterize associations according to tumor characteristics.