Results in this study underscore the substantial role of dementia in late-life disability and caregiving to older people. Data are from the 2011 National Health and Aging Trends Study. Among persons not residing in nursing homes, 78% of those with probable dementia received assistance with self-care or mobility activities or household activities for health or functioning reasons, compared with 42% of those with possible dementia and 18% of those with no dementia. Almost half of the 2.7 million older adults receiving help with three or more self-care or mobility activities have probable dementia. Relative to those with no dementia, they are more likely to live in supportive settings and to be low income, non-White, and widowed. One third of informal caregivers are assisting someone with probable dementia and account for 40% of informal care hours. They are three times as likely to report substantial negative impacts of caregiving as those caring for persons with no dementia. They are more likely to use some caregiver support services (respite, training, financial help) and also more likely to be looking for support services.