‘Nudging’ refers to a relatively new political steering approach that attempts to shape people’s choice architectures in such ways that they adopt certain desired behaviours without forcing, incentivizing or convincing them to do so. The proponents of the approach consider nudges highly effective and efficient instruments to address societal problems which are rooted in individual behaviour. Nudging is regarded as a particularly promising approach to tackle persistent unsustainable behaviour patterns in fields such as energy or food consumption. Yet, the discussion about the potential contributions of nudging to sustainability governance is only at its beginning. This chapter adds to the burgeoning discussion about ‘nudging sustainability’ in conceptual respects. It does so by critically reflecting on nudging from a theoretically informed sustainability perspective. The analysis reveals that there are important tensions between nudging and different sustainability conceptions. These tensions should be carefully taken into consideration in further research and practice on the role of nudges in sustainability governance.