Often considered dumping grounds for those who cannot function in mainstream schools, alternative education providers are seen as outliers in the provision of schooling. With schools as relatively stable workplaces, alternative education provision makes for a rich laboratory to further our understanding of the causal impact of schooling on a range of outcomes. They are naturally occurring experiments in schooling through interventions in instruction, curriculum and student cohort. Montessori school-based education in Australia is one such case. Experiencing a 31% growth in enrolments since 2009, they offer useful insights for different measures of education. A pre-requisite to such insights is a situational analysis of current provision. Drawing on an interview-based study with 20 Montessori school leaders, this investigation identified three problems and possibilities for schools working on the margins: (i) clarity about what is their distinctive form of education; (ii) building the collective; and (iii) evidencing quality of provision.