Background: Inclusive STEM (traditionally known to stand for "Science, Technology, Engineering, and Math") high schools are emerging across the country as a mechanism for improving STEM education and getting more and diverse students into STEM majors and careers. However, there is no consensus on what these schools are or should be, making it difficult to both evaluate their effectiveness and scale successful models. We addressed this problem by working with inclusive STEM high school leaders and stakeholders to articulate and understand their intended school models. This "bottom-up" approach is in contrast with other studies that have taken a "top-down," literature-based approach to defining STEM schools. Results: Through this process, we identified 76 critical components of STEM schools and derived a theoretical framework of eight elements that represent the common goals and strategies employed by inclusive STEM high schools across the country: Personalization of Learning; Problem-Based Learning; Rigorous Learning; Career, Technology, and Life Skills; School Community and Belonging; External Community; Staff Foundations; and External Factors. This framework offers a clear picture of what exactly inclusive STEM schools are and common language for both researchers and practitioners. Interestingly, STEM disciplinary content did not emerge as a defining component across school models. Conclusions: Findings suggest that STEM school leaders and stakeholders view their STEM school identity as rooted in pedagogy, transferrable skills, school culture, and rigorous instruction across all subjects, including, but not restricted to, STEM. This raises questions about the goals of inclusive STEM high schools and the STEM discipline outcomes that we should reasonably expect to see from STEM schools.