Within ecological economics there is recognition of the need for new approaches to decision-making to support sustainable development initiatives. There is an increasing acknowledgement of the limitations of cost–benefit analysis approaches as a measure of the (un)sustainability of organizational activities. These are viewed as particularly inappropriate within the participatory settings that sustainable development proponents seek to foster. They also fail to deal with the highly contested nature of sustainable development discourse in contemporary pluralist democracies. While advances have been made in the field of multi-criteria decision-making, there is still a relative dearth of versatile models that accommodate monetization in a way that recognizes the limits of calculative technologies. This article introduces readers to developments within the accounting discipline designed to support sustainable development decision-making and evaluation. In particular, it proposes sustainability assessment models as a viable alternative to cost–benefit analysis. Sustainability assessment models are based on an inter-disciplinary approach that recognizes the need for “accountings” that facilitate more participatory forms of decision-making and accountability. As such, they address many of the weaknesses in current approaches to cost–benefit analysis. The authors’ first experiences with sustainability assessment models were with BP and the United Kingdom oil and gas sector, where models were developed as a means of making previously external costs more central to organizational decision-making. Later work has included exploration of a range of decision-making situations in private and public sector organizations in both the United Kingdom and New Zealand. This has involved more explicit attention to plural values and issues of participation, dialogue and democracy.