The UN system has evolved over three-quarters of a century to take on many new problems since 1945 and to address many of the critical risks that have emerged. Conventions have been negotiated and signed, specialized agencies created, and programs and structures established within the UN Secretariat. With globalization, these multiple problems have become increasingly interrelated, leading to new vulnerabilities at the global level, with threats of systemic collapse. Specialization needs to be balanced by increased integration. A strengthened UN system with legislative capacity would be able to build on this important capacity to coordinate, combine and help these many entities to evolve into a more efficient and coherent system. The Sustainable Development Goals provide the latest globally accepted definition of sustainable development and a useful framework for the scope of the required international governance. The goal to leave no one behind helps to focus on the needs of the poor, the marginalized, disabled, migrants and women, too often excluded from governmental responsibility. Their situation needs to be monitored with disaggregated data and addressed through shared responsibility at the multiple levels of governance. UN reform needs to build in mechanisms for flexibility and adaptability to new and emerging global risks.