Drawing on theories of agency in LPP (e.g., Bouchard and Glasgow, in: Bouchard, Glasgow (eds) Agency in language policy and planning. Critical inquiries, Routledge, 2019) and educational governance (e.g., Ramiel and Lefstein in Camb J Educ 52(2):217–233, 2022), this study investigates the conditions under which heritage language schools operate outside national support structures. It is based on a linguistic ethnographic case study of a Greek community-run complementary school in Sweden that abruptly lost access to its premises in the spring of 2023. We examine the key stakeholders’ understandings of this period of turbulence, and the individual and collective agentive responses they enacted to secure the school’s survival and to overcome adversity. Data were collected over two years and include policy documents, interviews with key stakeholders, fieldnotes and recordings of classroom interactions, as well as fieldnotes from board, parent and teacher meetings. The findings exemplify how bottom-up governance practices, individual and collective agency and emotional investments contribute to the Greek school’s organisational sustainability, and enable it to persist in the face of acute challenges and the changing political conditions in Sweden. Ultimately, we discuss how these findings can inform language policy more broadly to strengthen support for heritage language education and multilingualism in society. © The Author(s) 2025.