The household and family structures are determinants in a number of integration outcomes. Studies have shown, for example, that the home environment (whether parents are present and the size of the family) has an impact on children’s school performance, which in turn affects their economic integration later on. Family structure also determines such living conditions as income and housing as well as the ability of adults to both work and support their children.The integration outcomes of households that are solely composed of immigrants differ significantly from those of mixed households (where one mantainer is immigrant and the other native-born) – with the latter broadly resembling those of native households. Beyond socio-demographic characteristics, a prerequisite for understanding the outcomes of the foreign-born is thus to understand the differences between their household structure and that of the native-born.This chapter volunteers two definitions of immigrant household and goes on to analyse the size of such households () and their composition ().Throughout this publication, reference will be made to the background information presented in this chapter so as to explain certain defining immigrant characteristics. For further discussion of issues raised by the indicators considered, see the section entitled Data limitations at the end of the chapter.