How do legal regulations, individual behavior, and societal understanding of 'parental custody' fit together? Against the backdrop of the current legal debate surrounding joint custody for unmarried parents, this book documents the latest scientific findings. It presents, among other things, evaluations of official statistics, particularly the results of its own quantitative and qualitative surveys of parents who were not married at the time of their child's birth, as well as relevant professionals from registry and youth offices. These findings are discussed in the context of legal analyses that include an international comparison and the historical development of the law. The content covers non-marital births in Germany, custody arrangements for non-marital births, and an analysis of the legal situation.