Approximately 2.3 million children in the United States live separately from both parents; 70-90% of those children live with a relative. Compared with children living with one or both parents, children in nonparental care are in poorer health, are at heightened risk for experiencing disruptions and instability in caregiving, and are vulnerable to other social antecedents of child health (e.g., neglect, poverty, maltreatment). Given the significant impact of adversity in childhood on health across the lifespan, which is increased among children in nonparental care, it is informative to consider the health risks of children living in nonparental care specifically. Research examining the contributions of poverty, instability, child maltreatment, and living in nonparental care, including meta-analyses of existing studies, are warranted. Longitudinal studies describing pathways into and out of nonparental care and the course of health throughout those experiences are also needed. Despite these identified gaps, there is sufficient evidence to indicate that attention to household structure is not only relevant but also essential for the clinical care of children and may aid in identifying youth at risk for developing poor health across the lifespan.