An emerging view in public policy is that there should be greater use of evaluations and randomised controlled trials (also known as RCTs). While RCTs have been shown to provide reliable estimates of causal impacts, there is little evidence on support for such trials amongst the general population. This paper provides the first large-scale survey evidence on knowledge and support for RCTs in a high-income country, and how this support varies across the population There is a relatively low level of familiarity with RCTs, particularly amongst older Australians and those with lower levels of education. When RCTs are explained to the general public, they are supportive in principle of them being used, more so than people are supportive of pilot programs without a comparison group. We also present analysis from an online survey experiment that tested the level of support, and factors associated with support, for policy trials and RCTs. In an experimental setting, the proposed policy area and support from experts had large effects on the level of public support. We conclude that experts and policy makers need to engage with the community to explain the benefits, and to learn from community concerns.