The interconnectedness and indivisibility of the 2030 Agenda and the realities of the world in which we work require us to deal with complexity at an unprecedented scale. As such, we need to identify, understand and develop appropriate ways of applying systems thinking to collectively define and address the challenges that we confront. We need to think across and beyond one area of expertise or mandate and to understand how our actions contribute to the overall United Nations objectives. We need to analyse the environment as a set of complex, live ecosystems and to understand underlying organizing principles as well as the linkages, interactions, dependencies and power distribution among components and constituencies. And we must strategically identify leverage points in these systems to achieve maximum impact. United Nations leaders must therefore shift from linear thinking to non-linear, systems thinking.