This chapter discusses the origins of STEM high schools in the U.S. and how they were stimulated by grassroots level economic needs, funding from private foundations, and state-level governmental initiatives. Policy makers offered policy supports for STEM schools that emphasized the twin goals of preparing more students for STEM careers, and better access to high quality STEM education for all students, especially those have been underrepresented in STEM fields. Inclusive STEM high schools (ISHSs), have sprung up across the U.S., although no umbrella organization nor an agreed upon model had been established for these educational experiments. Although some researchers documented instances where inclusive STEM schools failed to live up to their promises, others went on to show how successful ISHSs were organized. Carefully done quantitative research demonstrated their promise, especially as an alternative to traditional comprehensive high schools. Research showed that successful ISHSs had in place a strong STEM focused curricula, highly qualified, collaborative teaching staffs, supports for students underrepresented in STEM, and administrative structures open to innovation and flexibility. ISHSs also created positive school cultures, becoming STEM learning communities where diverse learners felt supported and valued as they developed the academic background and interpersonal skills to be successful in STEM in college and in careers.