Behavioural science shows that we are susceptible to many biases and influences that can, in certain contexts, lead to erroneous judgments and disadvantageous choices. As a result, various strategies have been proposed to improve human decision-making, such as debiasing, entrusting choice to algorithmic systems, or changing choice environments. In my talk, I will focus on the latter strategy, in particular the nudge programme and similar interventions. I will first present the basic claims of the nudge programme, which aims to modify people’s behaviour by changing choice environments without eliminating freedom of choice. I will then discuss some challenges and open questions related to the design and implementation of nudges. Should we put more emphasis on examining how (individual) decision-makers relate to the environments within which they make choices? What implications does the complex nature of decision-maker-environment interaction have for the design (and implementation) of nudges? How ethically problematic is deliberate steering of peoples’ behaviour, and when should we support it, if at all?