CHARM explores the ecosystem of Finland's oldest written culture, emphasising the transformative impact of writing during the Middle Ages. Despite the crucial role of texts in connecting Finland to the Christian and Latin cultural sphere, local practices of writing remain poorly known. CHARM will conduct a large-scale survey focusing on the three major writing centres Turku, Naantali, and Viipuri in the 15th century, breaking traditional boundaries in three innovative ways. It integrates humanities and methods from natural sciences, explores beyond textual contents to include writing support and inks, and examines both book fragments and charters together. This comprehensive approach unveils nuanced processes in adopting and modifying writing practices, contributing to a deeper understanding of Finland's early cultural history.