This project provides the first comprehensive investigation into the experiences of people with dementia (PWD), their carers, and the staff who provide care in emergency departments (ED) in the UK. This is a mixed methods study which used a national survey (N=403) followed by ED observation (32 hours) and qualitative interviews with health professionals (N=29), in an iterative and sequential design to present a holistic evaluation of the current experiences of the key parties- patients, carers, and ED staff involved in receiving and providing care. The theoretical perspective of the Human Factors Approach to patient safety underpins this work. The project included people with dementia and carers as collaborators and co-designers in both the development of the research tools and in shaping the project outputs. This research explores the barriers and facilitators to safe and effective care, concluding that here are a number of barriers (poor integration of communication systems, inappropriate physical environments, misalignment of staff training and workplace staffing models), which may affect the healthcare team’s ability to provide effective dementia care. These systemic challenges both give rise to and exacerbate poor organisational and safety cultures. However, despite these challenges, there are examples of safe and effective care (positive deviants) where uncommonly good outcomes for this patient population are achieved. Examining these examples offers valuable insight into potential adaptions, which could be used to improve existing care.