ObjectivesTo compare the experiences of people with dementia living alone or with others and how these may change over two years. DesignWe analysed longitudinal data from three assessment waves, one year apart, in the British IDEAL cohort. SettingParticipants with mild-to-moderate dementia were recruited through National Health Service providers, where possible with a family caregiver, and interviewed at home. ParticipantsThe current analyses include 281 people with dementia living alone and 1,244 living with others at baseline; follow-up data were available for 200 and 965 respectively at time 2 and 144 and 696 respectively at time 3. For those living alone, 140 nonresident caregivers contributed at baseline, 102 at time 2 and 81 at time 3. For those living with others, 1,127 family caregivers contributed at baseline, 876 at time 2 and 670 at time 3. MeasurementsAssessments covered: cognitive and functional ability; self-reported perceptions of health, mood, social engagement, quality of life, satisfaction with life and well-being; use of in-home and community care; and transitions into residential care. ResultsPeople living alone tended to have better cognitive and functional ability and were more frequent users of in-home care. However, they experienced poorer physical, social, and psychological health and reduced quality of life, satisfaction with life, and well-being. These differences persisted over time and rates of transition into residential care were higher. ConclusionsTo facilitate continuing in place for people with dementia living alone, a dual focus on supporting functional ability and addressing psychosocial needs is essential in the context of an enabling policy framework.