There has been some significant progress made towards achieving the Sustainable Development Goals (SDGs) since their adoption in 2015. Notwithstanding this progress, gathering storms of weakening global economic growth, rising income inequality, unabated global warming and climate change, and escalating conflict are posing serious threats to SDG implementation. On the other hand, rapid technological advances, especially renewable energy technologies, offer some hope for accelerating SDG progress. Sustainable Development Outlook 2019: Gathering Storms and Silver Linings identifies some of these key challenges and underscores the imperative of bold and urgent policy actions for addressing them. It identifies the interlinkages among these challenges, highlighting the need for addressing them with an integrated approach instead of tackling them as stand-alone challenges to be resolved sequentially and in isolation. The challenges highlighted here, of course, not only undermine SDG progress; they also risk changing the overall context of sustainable development, and, because they cut across all the SDGs and affect all countries, they can potentially undermine the overall implementation of the 2030 Agenda for Sustainable Development.