Dementia is an illness that raises important questions about our own attitudes to illness and aging. It also raises very important issues beyond the bounds of dementia to do with how we think of ourselves as people - fundamental questions about personal identity. Is the person with dementia the same person he or she was before? Is the individual with dementia a person at all? In a striking way, dementia seems to threaten the very existence of the self. This book brings together philosophers and practitioners to explore the conceptual issues that arise in connection with this increasingly common illness. Drawing on a variety of philosophers such as Descartes, Locke, Hume, Wittgenstein, the authors explore the nature of personal identity in dementia. They also show how the lives and selfhood of people with dementia can be enhanced by attention to their psychosocial and spiritual environment. Throughout, the book conveys a strong ethical message, arguing in favour of treating people with dementia with all the dignity they deserve as human beings. The book covers a range of topics, stretching from talk of basic biology to talk of a spiritual understanding of people with dementia. Accessibly written by leading figures in psychiatry and philosophy, the book presents a unique and long overdue examination of an illness that features in so many of our lives.