This chapter offers some personal thoughts on the use of Quantified Risk Assessment (QRA) as an aid to decision-making, particularly for decisions by society beyond the technical sphere. Initially Health and Safety Executive relied on an assessment of the consequences of the worst reasonably foreseeable accidents, giving hazard ranges which defined the zones where there seemed possibly to be significant cause for concern. It seems necessary to begin by noting that the results of QRA may be used in a wide variety of situations, from plant design options to high-level policy. In all cases where the use of QRA is not routine, some care is needed in deciding the approach and the degree of sophistication to be applied. The basic objective of the assessment is to show the risk to an individual living in a house at a particular location near a major hazard.