The Leave No One Behind pledge lies at the heart of the SDG framework – a commitment ‘to reach the furthest behind first’ and ensure that targets are met for all segments of society. Monitoring and delivering on this promise is not just a matter of equity and fulfillment of fundamental children’s rights. It is also a condition for achieving the 2030 goals. Failure to narrow the gaps between the most marginalized children and the rest of society is acting as a brake on progress. To illustrate this globally, this report presents inequality trends for five key child poverty indicators – child mortality, malnutrition, child marriage, birth registration and primary education. focusing on the Leave No One Behind pledge and what it could look like in practice. It proposes steps that could be taken by technical stakeholders involved in SDG monitoring and review processes.