Purpose: This paper explores the context within which experimental, pedagogically progressive schools were established in Australia during the first decades of the 20th century. Design/methodology/approach: The paper presents a case study of the establishment of Rosbercon Girls' Grammar School. It draws on educator accounts, archival documents and contemporary literature to provide a brief narrative of the events leading to the opening of the school; to sketch the family of educators who were pivotal in making it a reality; and to identify key aspects of the social and legislative context that made such an initiative possible. Findings: Rosbercon was established at a time when a modest school could be established relatively easily by a small group of educators with a shared vision. The early 20th century was a moment of national optimism in Australia, where an appetite for new educational ideas created a climate in which innovative educators found fertile soil for their pedagogical experiments and adaptation of emerging ideas from around the world. Their efforts were facilitated by an emerging global network of personal interactions, professional learning, professional associations and educational literature. Originality/value: This paper addresses the relative lack of scholarly examination of the origins of Rosbercon Girls' Grammar School, an institution that previous authors have identified as Australia's oldest experimental school. The case study also contributes to a broader appreciation of the trajectory of progressive education during the early 20th century.