FFCWS recruited a cohort of children born between 1998 and 2000 to investigate the effects of parental relationships and family structures on child outcomes. Babies of mothers who had just given birth were recruited from hospitals in 20 large cities across 18 states in the United States of America (USA). All recruited participants had 2 living parents and were expected to be living with one or more parents for the first 5 years of life. The mothers, fathers and primary caregivers of the participants were included in the study to provide information on participant children. At baseline, over 4,800 participants were included in the study. Over the course of the study, childcare providers and teachers were also interviewed to provide information on participants. In the 7th wave of data collection at 22 years, the children of participants were also included in the study.