The socio-demographic profile of lone parents has changed in the last decades. Being mostly widowed men and women or young single mothers until the 1970s, lone parents are nowadays mostly divorced and separated parents, even though they are still by and large mothers rather than fathers. As a consequence, the experience of lone parenthood has also dramatically changed. Less objects of pity or stigmatized with shame, lone parents and their children are more than ever bound by legal arrangements to the other parent and are caught in more dynamic family trajectories.There are at least two remarkable changes that certainly need to be addressed by research on lone parenthood: its boundaries and its diversity. Both aspects are connected and have potential implications for lone parents and their children. First, the diversity and complexity of legal and residential arrangements of parents and children make it difficult to establish the borders between a full-time and a part-time one-parent household. When child custody or parental authority are shared, can we still talk about lone parents? Children circulate more and more between two or more parental households after separation, and more than one parent may be financially and legally responsible for them. One direct consequence of such changes in the