Background: Improvement in the quality of end-of-life care for advanced dementia is increasingly recognized as a priority in palliative care. Aim: To evaluate the impact of a multidimensional intervention to improve quality of care and quality of dying in advanced dementia in long-term care facilities. Design: Quasi-experimental study with the intervention taking place in two long-term care facilities versus usual care in two others over a 1-year period. The intervention had five components: (1) training program to physicians and nursing staff, (2) clinical monitoring of pain using an observational pain scale, (3) implementation of a regular mouth care routine, (4) early and systematic communication with families about end-of-life care issues with provision of an information booklet, and (5) involvement of a nurse facilitator to implement and monitor the intervention. Quality of care was assessed with the Family Perception of Care Scale. The Symptom Management for End-of-Life Care in Dementia and the Comfort Assessment in Dying scales were used to assess the quality of dying. Participants: A total of 193 residents with advanced dementia and their close family members were included (97 in the intervention group and 96 in the usual care group). Results: The Family Perception of Care score was significantly higher in the intervention group than in the usual care group (157.3 vs 149.1; p = 0.04). The Comfort Assessment and Symptom Management scores were also significantly higher in the intervention group. Conclusions: Our multidimensional intervention in long-term care facilities for patients with terminal dementia resulted in improved quality of care and quality of dying when compared to usual care.