Generally, adult children are perceived to have obligations to support their parents, but now that divorce and remarriage are common phenomena, the question arises to which parent-figures this norm applies. We derive hypotheses on normative obligations towards step-parents and biological parents and the role of co-residential history and divorce. From the perspective of remarriage as an ‘incomplete institution’, we argue that obligations towards step-parents are more ambiguous and therefore more conditional. We collected unique vignette data (N = 4,783) as part of a nationally representative Dutch panel study and predicted norms on adult children’s obligations to provide socio-emotional and practical support using fixed-effects models. We f...