Abstract In eighteenth-century, colonial Sri Lanka, the Dutch church kept extensive registers of the local population. These “school thombos” contain individual registration of baptism, marriage, school attendance and death. This article argues that the school thombos reveal moral control over family life by the Dutch East India Company and the Dutch Reformed Church, while offering locals a legal and religious identity to employ in negotiating the Dutch colonial bureaucracy. These rarely studied registers shed new light on Sri Lankan family history and the practices of Dutch colonialism. What do they tell us about conjunctures of locals with colonial religion in eighteenth-century Sri Lanka? The school thombo was an instrument used to register and regulate family life, with specific functions and uses by different actors. This article explores the format, objectives and use of the school thombo. Why was the school thombo created and who were registered in these sources? What were the micro practices of drawing up the school thombo? The article is supported by several case studies that illustrate how the school thombo found its way into family life while demonstrating the value of written identities.