Current patterns of family formation in Australia mean that significant numbers of children are growing up in families include step-parents or step-siblings, or are headed by cohabiting rather than married parents. Further, these families may extend beyond the one household. It is this situation that is explored in this paper, with a focus on how fathering of young resident children differs when fathers have children living in another household. It is expected that when a father has children living in another household, his capacity to be involved with children living within the current couple-family may be somewhat diminished. This paper explores to what extent this is true, by examining father involvement using Growing up in Australia: The Longitudinal Study of Australian Children (LSAC). Multivariate analyses of these data found that on some aspects of father involvement, those fathers with children living elsewhere did have diminished levels of involvement. Partnered fathers with children living elsewhere were less involved in some aspects of care of resident children. Children in these families had less time in the day when they were with their father without their mother also present. Further, fathers who had children living elsewhere spent less time doing child care tasks. These findings were apparent in multivariate analyses, which also took account of a wide range of family, parental and child characteristics.