This paper compares the wellbeing of children in married- and cohabiting-parent families. It examines the impact of cohabitation as a setting for raising children, by investigating the different family characteristics, parenting practices, inter-parent relationships, family stability and transitions, and socioeconomic characteristics of married and cohabiting parents, as well as single parent families. Data is taken from 'Growing Up in Australia: The Longitudinal Study of Australian Children' (LSAC), for families with young children over a four year period, from children aged 4/5 to 8/9.