AbstractDifferent family migration strategies and immigration policies may lead to the separation of family members and the formation of transnational families, some of which end up reunifying later on in the country of destination. Despite the growing interest in this issue, no systematic large‐scale study has analysed to what extent child reunification patterns vary among family types, but also in distinct policy contexts. In this paper, we examine the reunification patterns of children left‐behind by parents who migrated to France and Spain in order to understand whether children from standard two‐parent families differ in their chances of joining their migrant parents in the destination country compared to children in non‐standard families (single parent and blended families), as well as the potential role of immigration policies on these chances. We base our analyses on recent nationally representative surveys of immigrants in the two countries (TeO 2008 and ENI 2007), complemented by indicators on immigration policies coded in the ImPol database produced within the TEMPER project. We find that children belonging to non‐standard families are left‐behind for longer periods of time than those in two‐parent families, even after controlling for migrant parents' socio‐economic resources. Our results equally point to a disconnection between the procedure legally defined for family reunification of children and their actual migration trajectories, as well as an important role of regularizations in facilitating the family reunification process.