Project Summary/Abstract The proposed research focuses on estimating the prevalence of informal dementia caregiving and determining the dose-response effect of dementia caregiving burden on outcomes in the Understanding America Study (UAS), a large online panel representative of the U.S. adult population. In order to pursue these goals, we will leverage the UAS infrastructure of the data collected in the UAS, both of which have been greatly enriched by the work we have been carrying out under the parent grant 1 U01 AG054580-01A1 ”Toward Next Generation Data on Health and Life Changes at Older Ages”. For this reason, we request an administrative supplement to the parent grant to accomplish three important research objectives. First, we will estimate the prevalence of informal caregiving in a population-representative sample, where survey participants self-report the extent of informal caregiving they provide. This approach is different from that of other surveys, where caregivers are identified by respondents receiving help with particular daily activities. Online survey administration in the UAS will enable us to regularly update prevalence estimates at a relatively limited cost. Second, in collaboration with the Stress Measurement Network, we will develop a comprehensive questionnaire to effectively measure caregiver burden and stress over time. We will complement this information with an Ecological Momentary Assessment (EMA) of mood and stress, using the mobile app we developed under the parent grant. Third, we will monitor health, wellbeing, and economic circumstances over time and compare levels and changes in outcomes of dementia caregivers with those of non-dementia caregivers as well as non-caregivers. Since study participants are members of the UAS, they can be surveyed beyond the duration of this project as long as they remain in the panel. In the future, this may represent a unique opportunity to gauge potential long-lasting consequences of caregiving for the wellbeing of those who are not currently assisting dementia patients, but have done so in the past.