The Breakthrough Fellowship Award supports recent doctoral or medical graduates in pursuit of innovative, high-impact breast cancer research during their postdoctoral fellowship and allows them to obtain the necessary experience for an independent career at the forefront of breast cancer research. Those individuals should be exceptionally talented researchers who have demonstrated that they are the “best and brightest” of their peers. Applicants for this award must exhibit a strong desire to pursue a career in breast cancer research, with clear evidence for a researcher development plan that will lead to a successful independent career in breast cancer. Applicants must also demonstrate that the proposed research has high potential to lead to or make breakthroughs in breast cancer. The critical components of this award mechanism are: Impact: Research supported by the Breakthrough Fellowship Award will have the potential for a major impact and accelerate progress toward ending breast cancer. The impact may be nearterm or long-term, but must be significant and move beyond an incremental advancement. Applications must articulate the pathway to making a clinical impact for individuals with, or at risk for, breast cancer, even if clinical impact is not an immediate outcome. Principal Investigator (PI): Under this award mechanism, the postdoctoral fellow is considered the PI and, as such, should write the project narrative, researcher development plan, and other application components, with appropriate guidance from the mentor. While the PI is not required to have previous experience in breast cancer research, the proposed project and researcher development plan must focus on breast cancer. Applications must emphasize the PI’s high potential for success in becoming an independent breast cancer researcher based on his/her qualifications, achievements (including first-author publications), and letters of recommendation. Mentor: The mentor (or co-mentor, if applicable) must possess the appropriate expertise and experience in breast cancer, to include recent publications and active peer reviewed breast cancer funding, and clearly demonstrate a commitment to guiding the PI’s research and development as a researcher. If the mentor is not an experienced breast cancer researcher, then formal comentorship by an established breast cancer researcher is required. The application must include information about the mentor’s experience in conducting innovative research and how he/she intends to support the PI’s endeavors in breast cancer. Mentorship by an investigator without an established record of mentoring pre- and/or postdoctoral trainees may be offset by the overall strength of the researcher development plan. Researcher Development Plan: Applications must provide details on the suitability of the PI’s research project and overall researcher development plan for attaining the goals of this award mechanism. The research project should be based on a sound scientific rationale and/or a thorough review of the literature. Preliminary data are allowed, but not required. Applications must elaborate on the qualities of the research environment in which the candidate will work, provide details on the individualized breast cancer-focused researcher development plan, and describe how it will facilitate the PI’s career development as an independent, innovative breast cancer researcher. A multidisciplinary research approach to breast cancer is highly encouraged, but not required; however, if there are multidisciplinary aspects, they should be clearly outlined in the application.