This policy brief provides an overview of key concepts of complex adaptive systems – and why understanding them is important for modern Australian society. An approach called 'systems thinking' is described as a tool for making sense of a changing world. Implications of complex adaptive systems and systems thinking, though relevant for any sector or individual, are framed here in the context of leaders, organisations, governments and citizens. The key message is that the way we think about complex adaptive systems needs to be different from the way we think about simple systems. We also need different skills to thrive.