A mining project would take up habitat that is part of the home range for local deer. The habitat would be lost for the duration of mining and some rehabilitated after closure. Is this impact acceptable or not? In IA terms, this is the “significance” question. Significance frames the question in terms of benchmarks or thresholds beyond which an impact could be con-sidered unacceptable in the environmental and social context of a project. Assessments of impact significance are central to IA and to decision-making about projects.