The majority of women who get breast cancer have none of the known risk factors. Despite all the research that has been done, we still do not know what causes breast cancer or how to prevent it. We need to look more broadly for hints we may have missed in the past. The HOW Study allows us to search for, and find, such “hidden” risks and gain new insights into what causes breast cancer. Because HOW participants include a large and diverse group of both breast cancer survivors and those who have never had the disease, we are able to explore previously unknown risk factors for the disease, factors that contribute to long-term survivorship, and quality of life post treatment.