Background. Dementia not only has a negative effect on a person’s well-being, but it also affects the well-being of their relatives. In this study, we examined how relatives perceive the well-being of people with dementia who live in nursing homes and how nursing staff contribute to the well-being of the residents they care for. Method. A qualitative study with a phenomenographic approach was applied. Ten individual semistructured interviews were conducted, five in Sweden and five in Hungary. In this study, the COREQ checklist for qualitative studies was followed. Results. The perceptions relatives had of what constituted well-being resulted in five categories of factors that could impact negatively or positively on a person’s well-being: “Nursing care is adapted to the needs of the person with dementia,” “Nursing is carried out by a sustainable care team,” “The social needs of the person with dementia are met,” “The person with dementia participates in meaningful activities,” and “The person with dementia shows signs of feeling well.” Conclusion. From relatives'’ perspective, well-being can be created for people with dementia if nursing is person-centred and managers allow staff more time to socialize with the person with dementia. Relatives are essential cooperative partners in person-centred dementia care. Relevance to clinical practice. Person-centred care is essential. Relatives, nurses, and managers are important partners in making it possible. Competence in dementia and knowledge of values and ethics are needed to provide autonomy and well-being. Patient or Public contribution. Ten relatives were selected through purposive sampling. In Hungary, the relatives were invited to take part in the study and given information about it by an operational manger. In Sweden, this process was carried out by a dementia nurse. Transcribed content of semistructured interviews was analyzed using a phenomenographic method.