Abstract: In the past decade, policymakers have increasingly used behaviourally informed policies, including “nudges,” to produce desirable social outcomes. But do people actually endorse those policies? This study reports on nationally representative surveys in five countries (Belgium, Denmark, Germany, South Korea, and the US) carried out in 2018. We investigate whether people in these countries approve of a list of 15 nudges regarding health, the environment, and safety issues. A particular focus is whether trust in public institutions is a potential mediator of approval. The study confirms this correlation. We also find strong majority support of all nudges in the five countries. Our findings in general, and about trust in particular, suggest the importance not only of ensuring that behaviourally informed policies are effective, but also of developing them transparently and openly, and with an opportunity for members of the public to engage and to express their concerns.