BackgroundCognition and the ability to take care of daily activities and oneself gradually declines among people with dementia. Studies are scarce, especially regarding how people with young-onset dementia (YOD) (<65 years) experience the quality of their lives with the progression of dementia. People with dementia living alone face special challenges.AimTo examine the experience of the quality of life with YOD as a single person.MethodThe study presents a longitudinal case study with in-depth interviews exploring the experiences of a person with YOD. Individual interviews were conducted seven times over a period of three years from 2014 to 2017.FindingsWe examined if and how seven themes concerning the quality of life and well-being were fruitful for understanding the experiences of dementia in the everyday life of a single individual. The study explored needs and challenges during the development of dementia, and how the person reacted over time, set in context. The themes significant for well-being are: identity, connectedness, security, autonomy, meaning, growth and joy.ConclusionThe study shows how treatment, support, and services must be individualized when dementia develops in order to support identity, resources and mastering capacity, and promote well-being.