This study is based on the first wave of data on the child cohort (nine year-olds) in the Growing Up in Ireland (GUI) survey. It examines family relationships and their associations with parent and child well-being in the families of the nine year-olds and explores social inequalities in these aspects of family circumstances. The analysis is presented under five headings: the structure of families (a term which encompasses family structure both currently and over time and also includes family size), relationship quality between parents, the individual well-being of parents, relationship quality between parents and children, and the well-being of children.