The Careers in Science Intern Program hosted by the California Academy of Sciences provides San Francisco high school students from communities underrepresented in the sciences with transformative and meaningful STEM-based and workforce development experiences. Over two to three years, paid interns gain a robust set of skills through specialized training, individual mentorships, and project groups with support from Academy scientists and visiting professionals. The program helps interns develop skills to tackle complex ideas, learn to problem solve, and succeed in higher education. Lack of opportunity and historical bias within the STEM field has led to a lack of diversity in the workforce—a significant detriment to both the communities that are excluded from these opportunities and the scientific community itself. Careers in Science aims to increase and diversify America’s STEM workforce, contribute to the educational and career development success of participating youth, and increase science literacy and environmental stewardship among young people. Through the program’s 25 active years, it has been successful in inspiring and providing tools for success to hundreds of youths who may otherwise not have had access to high-quality STEM education and career growth opportunities. It is a powerful program that has changed, and will continue to change, lives for the participants as well as the face of STEM for the next generation.