Abstract
Recently, two prescription drugs (tamoxifen and raloxifene) have become salient to breast cancer prevention. With the advent of these drugs, referred to as “chemoprevention,” a mandate has emerged to classify certain women as high risk for breast cancer to determine a group of legitimate users of the drugs. This article examines the development and standardization of the model used to create such a group of high-risk women. The author argues that while the model remains uncertain and controversial, it has become the standard tool for the many jobs associated with legitimizing chemoprevention use in the United States. It has become the assumed standard—shaping practices, identities, and definitions—through its organizational embeddedness in the multiple practices and public images of chemoprevention despite its uncertainty and widespread critique.