The precautionary principle can require regulatory action in cases of potential environmental damage, even before conclusive scientific proof of harm has become available. Critics charge that this inherently puts the principle at odds with rational risk management, which should be based on sound science and cost-benefit analysis. This chapter clarifies the significance of the precautionary principle by answering a variety of criticisms. The precautionary principle is not anti-science; it calls for more and wider scientific investigation of poorly understood environmental phenomena. It does not oppose hazard assessments done by experts, but it does make experts answerable to a broader public. Yet the deliberative turn in implementing the precautionary principle does not expose it to charges of populism. By using standards such as proportionality and revisability, the precautionary principle promotes reasoned policy-making in cases where risks are insufficiently understood. Finally, precaution is not to be equated with prohibition. Precautionary measures include anticipatory actions such as intensified monitoring, increased safety margins, systematic labeling, and spatial planning that creates protected zones for certain activities. The complexity of precautionary action is a reflection of the complexity of our societies and of the links they create with nature.