SUMMARY Students from under-represented populations and/or disadvantaged backgrounds disproportionately fail to enter biomedical research at a PhD level, potentially because they lack research experience or self-identity as scientists. The long-term goal of PREP at UC Davis (PREP@UCD) is to prepare young scholars from these groups to succeed as academics and leaders in research. Specifically, we aim to provide PREP scholars with the research, communication, analytical, and life skills required to excel in doctoral programs in the biomedical sciences. We have reached our benchmark; 12 of 14 PREP@UCD alumni have been accepted to top biomedical PhD programs, with four alumni awarded NSF Graduate Research Fellowships to fund PhD study. Thus, PREP@UCD is significant because we successfully foster an inclusive scientific training culture that has led to retaining students from historically marginalized groups in biomedical science at the bachelors-to- graduate school interface and in PhD programs. The University of California, Davis, is an innovative setting for a PREP program because it combines high research funding from the NIH (over $250 million last year), high academic ranking (11th best public university in the country), and commitment to serving underrepresented (27% of undergraduates and 20% of biomedical PhD students) and first-generation students (42%). Six PREP scholars annually will participate in research (75%) and career development activities (25%) under the close guidance of a mentorship team consisting of research supervisors, a faculty advisor, the PI, and the program coordinator. Three specific aims are proposed to prepare PREP@UCD scholars for biomedical graduate programs. First, PREP will provide a mentored research environment where scholars can gain experience in performing individual, hypothesis-driven research. This will help to develop their self-images as scientists and thus foster success in graduate school. Second, PREP@UCD scholars will be trained in experimental skills to prepare them for graduate school and a career in biomedical research. Laboratory activities will develop skills in gathering scientific information, formulating and testing hypotheses, working in a team, solving problems critically, assessing research ethics and values, and learning technical skills. Third, PREP@UCD scholars will be empowered with strong professional skills. Each scholar will spend 25% of their effort in career development through communication exercises, grant writing, journal clubs, participation in research conferences, and workshops in professional skills, careers in biomedical science, ethics, rigor, and reproducibility. The skills and scientific self-identity fostered during PREP@UCD will provide the scholars with a better chance of excelling in biomedical PhD programs. The combination of the research expertise and mentoring experience of the trainers, and a focus on self-identity as a scientist in the laboratory, coupled with bro...