The article develops a discourse about equality for children and their recent evolution from adult-centred consideration to definition as a separate, critical constituency as stated in the Sustainable Development Goals (SDGs), with their child-focused goals and targets. Challenges implementing equality and fairness are discussed, from the World Summit for Children (WSC) in 1990 to the nearly simultaneous ratification of the Convention on the Rights of the Child (CRC), which gives children agency through its legally binding clauses, and the Millennium Development Goals (MDGs). The article reviews past lessons learned and the post-2015 agenda debate, from which worldwide agreement evolved about multidimensional poverty and an equality roadmap. The article suggests social accountability processes to achieve lasting SDG targets. It provides a methodology for implementing social accountability actions, accompanied by examples to mobilise communities and encourage child and youth participation at the local level.