Project Summary Disparities in health and well-being among children in families with different incomes emerge early in life. Children in poor families are born with worse health than their counterparts in higher income families, and this relationship between health and income becomes more pronounced through the life cycle. Children who experience worse health early in life also go on to have significantly lower educational attainment, health, and socio-economic status in adulthood. This relationship suggests that the intergenerational transmission of advantage that we observe within families could be driven by the good health that wealthy parents confer to their children early in life. Understanding how unequal parental incomes result in unequal health in childhood may therefore help us understand patterns of income inequality and intergenerational economic mobility more generally and also help policymakers make informed decisions about the efficacy of cash transfers. We propose to provide new evidence on the relationship between parental income and children's mental and physical health and well-being through the Y Combinator Research (YCR) Basic Income randomized controlled trial. The YCR experiment will provide $1,000 per month of supplemental income to a randomly-selected treatment group over a period of three years, with a control group receiving $50 per month over the same period. The 3,000 participants in the study have 3,640 children under the age 18 living in their household. We will survey participants about their children and leverage existing administrative datasets to obtain information on the impact of this income supplement on children's health outcomes. By comparing children of treatment group participants to control group participants, we will document how parental income affects the quality of the household environment and parental interactions (Aim 1), and investment in children's well-being including access to and use of medical care, food security, expenditures on enrichment and activities, neighborhood quality, and the quality of non-parental care (Aim 2) and childhood emotional, conduct, hyperactivity/inattention and peer relationship problems, pro-social behavior, achievement of developmental milestones, cognitive development and physical health (Aim 3). Our study will provide new, timely, and policy-relevant estimates on the impact of parental income on child health and well-being and the mechanisms through which this relationship operates.