Project Abstract The National Institutes of Health has a stated commitment to diversifying the national scientific workforce. While diversity has many dimensions, women and underrepresented minorities (i.e., black, Latinx, indigenous, and Pacific Islanders) are particularly underrepresented in Science, Technology, Engineering, and Mathematics (STEM) and health careers. Rather than ability, disparities in career entry for both groups are largely due to differences in motivation and “sense of belonging,” which have a significant impact on educational success and persistence to build a career in STEM and health fields. Research shows that adolescents who experience racism at work or in school have negative outcome expectations for future careers. Experiences with sexual harassment, in particular, among young women, and STEM-related gender bias uniquely contribute to lower STEM motivation. The goal of this proposal is to create an interactive digital resource, Step Up for STEM and Health Careers (STEP UP) that includes the key elements of a bystander intervention for high school students to acquire the skills, attitudes, and awareness to mitigate bias and sexual harassment in STEM and health learning environments and attain a positive STEM identity. STEP UP will be a state-of-the-art, theory-based (Theory of Planned Behavior) intervention, informed by the Social Cognitive Career Theory with a long-term goal of increasing representation of women and minorities in STEM and health careers.