Government officials can have a disposition to conceptualise the behaviour of policy target groups as stable, malleable, or something in-between. This paper hypothesizes these conceptualisations to influence preferences for policy instruments: Officials seeing behaviour to be more stable are hypothesised to prefer enforcement when aiming to change behaviour, whereas officials assuming behaviour to be more malleable are hypothesised to prefer information provision and behavioural instruments. Using a survey among local government officials from the Netherlands (N = 717), we tested these hypotheses in the context of compliance with rules to prevent the spread of Covid-19. Results show that officials assuming behaviour to be more stable preferred more enforcement and information provision to change behaviour than officials assuming behaviour to be more malleable. This may suggest that seeing behaviour as more stable leads officials to prefer more government intervention in general. Conceptualisations about the changeableness of behaviour were not related to preferences for behavioural instruments. Implications for government officials are discussed.