This document provides an overview and analysis of progress made towards achieving the Millennium Development Goals (MDGs) between 1990 and 2015. It finds that while significant progress was made in areas like child survival, nutrition, education, and reducing poverty, many of the most vulnerable children were left behind, and in some cases gaps between advantaged and disadvantaged groups widened. Going forward, the global community must learn from this experience by focusing on equity and targeting the needs of disadvantaged groups in order to achieve truly sustainable development and ensure all children have equal opportunities.