Few people inside or outside government have had a greater impact on public policy in Australia than Ross Garnaut. His report in 1990 provided a blueprint for Australia's economic 'engagement' with Asia, whether or not one agreed with its underlying logic and analysis. The reception of his report on climate change in 2011 could hardly have been more different. Why is it that some ideas enjoy wide support from influential actors and are enthusiastically taken up by policymakers, while others struggle to gain traction, even when backed by government? This paper provides some possible answers to this puzzle by identifying factors that facilitate or obstruct the influence and impact of 'policy entrepreneurs'