Globally, 850 million people lack identity documents, including birth certificates. Most of the world’s paperless people are living in poverty in rural areas and belong to ethnic minority groups or racialized peoples. Some 237 million children under the age of five currently lack a birth certificate, and risk joining the world’s 15 million stateless people. Within countries, gaps in birth registration coverage map closely onto existing social inequalities based on gender, race, ethnicity, class, and geographic location. Lacking documentation and proof of legal citizenship, they will be unable to enjoy the full range of human rights. A global push is underway to achieve universal birth registration by 2030 as part of the UN Sustainable Development Agenda. At the same time, states desperate to control human mobility are enacting increasingly restrictive migration and border control measures at and beyond the physical border. What happens when the unregistered cross international borders, and have children of their own? Or when borders are brought to the unregistered, who are then issued documents identifying them as not-belonging?