compelling themes, such as mechanisms underlying breast cancer subtypes and breast density, epigenetic alterations (heritable changes that do not involve changes in DNA sequences) that occur over the life course, and gene/environment interactions. Specific exploration of the impact of environmental factors on breast development also is needed because altered development may influence breast cancer risk. In addition, research must evaluate the impact of multiple risk factors and periods when the breast may be most susceptible to exposures. Finally, research is needed to explore how people understand environmental risk issues. Accelerating the research process will require fully utilizing high-throughput technologies that are capable of evaluating multiple potential risk factors simultaneously. Streamlined study protocols also are needed to enable scientists to quickly understand the potential of particular risk factors and environmental agents that cause breast cancer and conduct studies to test their hypotheses. In addition, rapidly deployable research funding mechanisms and resources are needed to address emerging issues related to breast cancer and the environment. Excellent examples of these types of mechanisms and resources exist, but could be enhanced and more fully deployed. 1-4 Breast Cancer and the Environment: Prioritizing Prevention 1 programs as well as efforts to expand interagency collaborations and public-private partnerships. Engage Public Stakeholders The Committee recommends that the research planning, implementation, and translation process include stakeholders who represent the public and affected communities at every stage. Advocates and community organizations have long played a direct role in establishing priorities for breast cancer research, securing funding, conducting and overseeing federally funded research, and disseminating and translating research information to patients and the general population. In addition, advocates have played an important role in the design and implementation of many studies focusing on breast cancer and the environment. Public representatives should be involved as partners in the design and implementation of research programs to ensure that the research addresses public needs and interests. Public representatives also are critical to ensuring that research findings are translated into public health and regulatory actions and in communicating research and intervention needs to a diverse public. Furthermore, as agencies develop and apply standards for testing the effects of chemical and physical exposures, public participation can provide information about the exposures of greatest concern to the general public and specific communities. To ensure effective translation and dissemination of breast cancer research findings as the field progresses, active participation of breast cancer advocates, community representatives, and members of the public in research planning and prioritization must increase. These stakeholders provide unique perspectives and expertise on research priorities, optimal modes of public engagement, and best practices for translating and disseminating research findings to the public. rapid progress in understanding breast cancer and the environment. These recent innovations, in addition to the study of biological mechanisms such as epigenetics, may help to explain how environmental factors influence breast cancer risk. We need to know how and when environmental exposures, singly and in mixtures, influence breast cancer risk and how this risk may vary at different exposure levels or doses. Plan Strategically Across Federal Agencies The Committee recommends that federal, state, and nongovernmental organizations coordinate and collaborate to accelerate the pace of scientific research on breast cancer and the environment. Federal research into breast cancer is a blend of studies conducted by government scientists and research supported by targeted grant and contract programs based on agency priorities or investigator-initiated grants. A limited number of federally directed research programs and investigator-initiated projects focus specifically on breast cancer and the environment. To close this critical gap, the Committee recommends that, as part of a national breast cancer prevention strategy (see recommendation 1), federal agencies plan strategically for breast cancer and the environment research to be developed across the government to foster innovation and collaborative science. Joint planning and better coordination of the efforts of both governmental and nongovernmental funding agencies would increase the visibility of research on breast cancer and the environment, promote the goal of breast cancer prevention, facilitate sharing of resources (e.g., funding, data, research tools), help identify the most critical scientific questions, and facilitate the monitoring of progress toward answering these questions. In implementing a federal breast cancer and the environment research strategy, the Committee sees the need for comprehensive research management tools to help conceptualize and guide planning and prioritization of future federal 1-5 Breast Cancer and the Environment: Prioritizing Prevention 1 Primary prevention of new breast cancer cases requires a focus on identifying and reducing exposures that