Background: Approaching families to discuss deceased organ donation authorisation has been considered one of the central stages of the organ donation process. Current evidence is fragmented and how these encounters as a social process occur in practice has not yet been deeply explored. Purpose: Conceptualise the process of approaching families for organ donation authorisation after brainstem death. Methods: Constructivist grounded theory study. Seventy-one participants, including healthcare professionals and families, were recruited from two large hospitals in Chile from 2017 to 2019. Observation notes, 80 documents, 27 interviews and 14 focus groups were included and analysed following constructivist grounded theory principles and practices until theoretical saturation. Results: Reading the family was developed as the core process to explain how nurse organ donor coordinators approach families to negotiate organ donation authorisation. The core has two dimensions, direct and indirect, which depend on teams’ beliefs (Wright and Bell, 2009) and institutional social norms and will define the family approach. Conclusion and Implications: Approaching families for organ donation involves a multidimensional process that intertwines professionals’ and families’ experiences. Understanding the process as social and relational unveils the complexities of caring for and supporting bereaved families beyond organ donation decision-making. This constructivist grounded theory informs nursing practice, education and policymaking, highlighting organ donation as a family experience and challenging the limitation of quantitative outcomes to evaluate this complex phenomenon.