Historically, the mission of science, technology, engineering, and mathematics (STEM) schools emphasized providing gifted and talented students with advanced STEM coursework. However, a newer type of STEM school is emerging in the United States: inclusive STEM high schools (ISHSs). ISHSs have open enrollment and are focused on preparing underrepresented youth for the successful pursuit of advanced STEM studies. They promise to provide a critical mass of nontraditional STEM students, defying stereotypes about who does STEM and creating positive STEM identities. In this article, we advance a conceptual framework designed to systematically capture the qualities of ISHSs that can provide exciting new possibilities for students and communities. An iterative review of the literature suggests 10 critical components that may work together across 3 dimensions: design, implementation, and outcomes. Our goal is to apply this framework in various school models to better understand the opportunity structures that emerge and to create a theory of action of ISHSs.