BACKGROUND AND OBJECTIVES: Collaboration between formal and informal caregivers is essential for providing good care to nursing home residents. Yet, ambiguity regarding mutual roles and responsibilities often impedes effective collaboration. To address this issue, we examined how formal caregivers, informal caregivers, and residents establish a moral understanding of their responsibilities, and how these understandings affect their triadic relationship. RESEARCH DESIGN AND METHODS: We conducted a responsive evaluation including 28 semi-structured interviews with formal caregivers, informal caregivers, and residents. Walker's expressive-collaborative model of morality (2007) was used as a theoretical lens to identify identities, values and roles in the triad. RESULTS: Formal caregivers were assigned more moral responsibilities in the care process than residents and informal caregivers, particularly regarding decision-making authority. Formal caregivers considered this justified, while informal caregivers generally desired more influence. The attitude of residents on this matter remained relatively unclear. The diverging views on moral responsibilities between formal and informal caregivers led to relational tensions, impacting mutual trust and recognition between them. DISCUSSION AND IMPLICATIONS: Walker's model of morality provides a deeper understanding of the moral dynamics underlying the collaboration between formal caregivers, informal caregivers, and residents. Traditional hierarchies and a mismatch between healthcare and family ethics are implied to hinder informal caregiver involvement. Our findings call for practical and cultural adaptations on different levels within and outside nursing home organizations to improve the triadic collaborative relationship.