This is the first in a planned series of United Nations Children's Fund (UNICEF) reports tracking progress on the child-related indicators in the Sustainable Development Goals (SDGs). The report highlights, through a data lens, the enormous task ahead for countries in meeting the 2030 Agenda for children. Through the development of projections to 2030, the report identifies areas where greater efforts are needed and reveals the alarming inadequacies of data to track progress. It also examines trends among subsets of children, including girls and boys, and children in urban and rural areas, to identify groups of children most at risk of being left behind. [For the Executive Summary, see ED590001.]