U.S. public schools systematically serve some student populations better than others. Higher expectations, more resources, more rigorous content and instruction, and priorities reflecting students' purposes for education support opportunity for some. Social unrest in the 1960s reframed diverse education outcomes for students as inequity, a problem for democracy and civil rights. In that milieu, public secondary alternative schools emerged as innovative response to this socially articulated and shared problem in public education. In the first decade of the 21st century, public secondary alternative schools (alternative schools) serve consistently around 2.3% of secondary students in the U.S., about 600,000 students annually. Institutional theory predicts that innovative organizations in highly institutionalized sectors, like U.S. public education, will not persist as heterogeneous alternatives. Current models (Greenwood, Suddaby & Hinings, 2002) describe an institutional change path for innovation to either institutionalization, institutionalized organizations in a field adopt the innovative structures and practices, or extinction as fad or fashion. But, alternative schools have persisted as heterogeneous alternatives for more than forty years. This study addresses the question, "what about the role of public alternative schools allows them to persist as peripheral heterogeneous organizations in the institutionalized field of U.S. public secondary schools?" A mixed methods approach to this study allows inquiry and analysis into multiple levels of the institutional dynamics: 1) an analysis of the history of alternative schools, as organizations that evolve to address unmet priorities for changing populations underserved by traditional school organizations, connects alternative structures and practices to stakeholders' alternative priorities for these schools; 2) a longitudinal analysis, of National Center for Education Statistics (NCES) demographic and resource data, describes trends in differences between traditional and alternative secondary schools in the U.S. and makes the case that alternative schools engage in their work with different student populations and different levels of resources; and, 3) two case studies explain work that is understood as important for different stakeholders in two, different type alternative schools. The accounts of that work legitimate school structures and practices, and the schools themselves. Findings trace alternative schools as innovation through the Stages of Institutional Change (Suddaby, et al., 2002) arguing for a third path of persistence for alternative heterogeneous organizations in institutionalized environments. Alternative schools address diverse priorities for public education in the U.S.; serve high-needs populations of students in much higher concentrations than regular schools and with fewer resources; and these schools may need to maintain their heterogeneity to effectively address the priorities of local constituent groups. Alternative schools stabilize the field by serving as safety net for students and as a pressure valve for public schooling. I.e., alternative schools address technical and normative problems in public education that require a response from constituencies significant enough to demand, at least, a persistent marginalized solution.