ABSTRACT Age-related decline in physical and cognitive health are pressing public health concerns. Developmental science shows that variation in adult physical and cognitive health is reliably associated with individuals’ early experiences in their families of origin. Risky families, characterized by greater conflict and lower-quality parenting, tend to disrupt psychosocial and biological functioning, resulting in increased risk for diseases, including Alzheimer’s Disease and Related Dementias (ADRD). Children who receive less warmth, support, and responsiveness from their parents typically have higher inflammation levels, blood pressure, and allostatic load, indicators that predict future cardiovascular problems. These pathways are also implicated in altered midlife cognitive functioning and confer risk for Alzheimer’s Disease and Related Dementias (ADRD). This project takes advantage of an unparalleled opportunity to further this important line of work on the significance of family experiences in adolescence for health outcomes in adulthood by conducting a follow-up into midlife of the Sibling Interaction and Behavior Study (SIBS). SIBS is a longitudinal study of 409 adoptive and 208 non-adoptive families. The offspring in these families have already completed intake (in mid-adolescence), and three follow- up assessments. In the first assessment of SIBS, already coded direct observations of parent-child interactions, as well as parent-reports and child-reports of the quality of the parent-child relationship, were acquired. The availability of these relationship data at a key developmental phase in an adoption cohort provides a strong platform for the addition of follow-up data on the target participants/younger generation (YG; M age = 38 years) and their parents/older generation (OG; M age = 71 years). Our overarching objective is to investigate the degree to which family experiences in adolescence predict key indicators of health in adulthood among adoptive and non-adoptive adults and their aging parents. Specific aims of this project include: AIM 1: Determine the longitudinal effect of adolescent family experiences on later physical health and cognitive functioning in adult children (YG) and their aging parents (OG); AIM 2: Model the environmental impact of adolescent family experiences on later physical health and cognitive functioning; AIM 3: (a) Test whether the effects of family experiences extend to subtle indicators of physical health; (b; exploratory) and are moderated by APOE status.