According to the Australian Bureau of Statistics (ABS; 2007) approximately one in ten couple families contain resident step-children. In Wave 3 of the Household, Income and Labour Dynamics in Australia (HILDA) survey, 13% of households had either residential or non-residential step-children, or both (Qu & Weston, 2005). In the United States, approximately 9% of married couple households, and 12% of cohabiting households contain resident step-children (Teachman & Tedrow, 2008). Step-family data are not collected in the New Zealand Census. However, 19% of the 1,265 child participants in the longitudinal Christchurch Health and Development Study had lived in a step-family between the ages of 6 and 16 years (Nicholson, Fergusson, & Horwood, 1999).