Recent research shows that interpretations and uses of the precautionary principle can exacerbate the relations between states. Indeed, the precautionary principle increasingly plays a pivotal role in explaining how actors position themselves on various issues related to health, safety and environmental (HSE) risks. However, the books under review tend to subscribe to the approach that separates out precaution from risk assessment. In contrast, it is suggested in this article that the precautionary reasoning is a distinctive view of risk regulation, which reworks rather than repudiates risk assessment. This turn might help scholars to embark on the difficult task of understanding the extent to which the precautionary principle affects how HSE norms on risks are crafted, the channels through which they spread and the mechanisms that enable them to operate effectively.