At the 2015 United Nations General Assembly, 193 UN member states unanimously adopted the 2030 Agenda for Sustainable Development, a global development agenda that lays out 17 Sustainable Development Goals (SDGs) to be achieved by 2030. The SDGs, which came into effect in January 2016, are a universal set of goals, targets and indicators that set out quantitative objectives across the social, economic, and environmental dimensions of sustainable development. Addressing critical sustainability issues such as poverty, climate change, inequality, economic development, and ecosystem protection, the SDGs will be implemented in all countries, across different territorial scales.Cities and human settlements will be key to achieving the global SDGs. The SDGs come into effect in a world that is increasingly urban, with a little over half the global population now living in cities. Urbanization has thrown up some of the world’s greatest development challenges, but it also has tremendous opportunities for advancing sustainable development. SDG 11 recognizes the central role of urbanization in sustainable development, and calls for ‘mak[ing] cities and human settlements inclusive, safe, resilient and sustainable.’ As one of the 17 SDGs that will shape public policy priorities and guide development finance flows for the next fifteen years, the ‘urban SDG’ provides a tremendous opportunity for cities to build robust partnerships and gain additional resources for advancing sustainable urban development.For mayors and local leaders that are working to improve the quality of life in urban environments, the SDGs provide a roadmap for more balanced and equitable urban development. All cities aim to increase prosperity, promote social inclusion, and enhance resilience and environmental sustainability. In this way the SDGs capture large parts of the existing political agenda in virtually every city. When aligned with existing planning frameworks and development priorities, they can strengthen development outcomes and provide additional resources for local governments.Localization refers to the process of adapting, implementing, and monitoring the SDGs at the local level [1]. While the specific role of urban and local governments in implementing the SDGs will depend on individual countries, their systems of decentralization and local government mandates, Chapter 2 describes four basic steps for getting started with SDG localization in cities:Step 1: Initiate an inclusive and participatory process of SDG localization. This includes raising awareness of the SDGs at the local level, setting the stage for multi-stakeholder discussion and involvement, and prioritizing sustainable development through strong political leadership and integrated governance arrangements.Step 2: Set the local SDG agenda. SDG localization is key to ensuring that no one and no place are left behind in the development of a more sustainable future. Cities need to adapt the global SDGs into an ambitious yet realistic local agenda, through evidence-based decision-making that is backed by public support and input.Step 3: Plan for SDG implementation. Implementing the SDGs to be achieved by 2030 will require goal-based planning that adopts a long-term, multi-sectoral perspective, and is supported by adequate implementation capacity and financial resources, and multi-stakeholder partnerships.Step 4: Monitor SDG progress. Disaggregated data systems are necessary to measure local progress on SDG indicators, and to review the efficiency of program implementation. Local monitoring and evaluation (M&E) systems ensure that SDG implementation remains on track, and support the development of local capacity for more responsive and accountable governance.Many cities across the world are already leading the way on sustainable development and climate change action, and are well equipped to implement the SDGs. However, urban and local governments often struggle to drive action on sustainable development due to a number of constraints. These include limited political and fiscal power, lack of access to development finance, low levels of institutional capacity, absence of robust multi-level government cooperation and integration, and the inability to attract or be part of strong multi-stakeholder partnerships. Without first acknowledging and addressing the challenges faced by local governments in many parts of the world, SDG localization will not benefit the majority of the global urban population, will fail to build sustainable governance structures, and will constrain the achievement of sustainable outcomes.As discussed in Chapter 3, cities and human settlements need to have adequate autonomy, capacity, and resources to effectively implement the SDGs. In the longer-term, decentralized governance systems will need to ensure that political and fiscal powers of local governments are commensurate with their responsibilities, and local government bodies need to develop the skills and capacities for delivering more integrated, sustainable outcomes. Government legislation and regulations need to prioritize and incentivize sustainable development, and strengthen local governance, both in small towns and large metropolises.At the same time, local governments too can work in partnership with private sector and civil society stakeholders to develop innovative financing mechanisms and service delivery models that balance the social, economic and environmental dimensions of sustainable development. The shift to sustainable development is an opportunity for urban and local governments to leapfrog traditional development trajectories to more inclusive, environmentally sustainable, and economically successful development pathways. For forward-looking urban and local governments, the SDG agenda is a powerful tool for mobilizing collective action around common goals that not only improve the quality of life for local residents, but also develops cities to become attractive investment hubs and political leaders in their own right.