Public policies/interventions impact on many areas of activity including areas beyond the main focus of them ; the costs and (dis)benefits falling on other areas of the economy,  government and/or private sector, and different individuals. However, there is no consensus on the appropriate way to analyse such policies/interventions to decide which are beneficial and should be implemented. One form of economic evaluation, cost-effectiveness analysis, has been widely used to inform decisions about policies/interventions which affect only a single sector where there is a single agreed output (as in most health care evaluations), however, its use for evaluating interventions with multi-sector impacts is limited. Cost-benefit analysis (CBA), another form of economic evaluation, based on welfarism, has been proposed as a method which allows the evaluation of policies/interventions where costs and benefits fall on several sectors, by aggregating costs and benefits into a given numeraire, normally consumption. However, a key weakness of CBA is it fails to acknowledge the relevance of sectors' budget constraints. This despite the process by which budget constraints are set being viewed as having (democratic) legitimacy. We consider how decisions on policies/interventions with multi-sectoral impacts could most appropriately be informed by economic evaluation. Two options are considered: first, where there is an implied or explicit social welfare function (which could be based on welfarist or extra-welfarist principles); and second, a societal decision making approach. We aim to demonstrate that trade-offs are inevitable and have to be made, but budget constraints cannot be ignored and shadow prices on budget constraints are central no matter which approach is accepted. We also consider whether compensation payments between 'losing' and 'gaining' sectors are a potential means of understanding the net benefit associated with policies with multi-sectoral effects, and whether it is possible, necessary or even appropriate in practice to make such payments.