There is concern about the adverse environmental impacts that arise from resource use associated with the provision of goods and services. Increased efficiency in resource use and adoption of sufficiency as a basis for consumption are possible responses. There has been a good deal of effort to enhance efficiency but little as yet to foster adoption of sufficiency. In part this reflects a difference with respect to quantification. There is a well-accepted approach for efficiency but not for sufficiency. This paper proposes an approach for sufficiency and illustrates it with a number of examples. It argues that adoption of this approach would enhance efforts to reduce resource use and provide an effective means to deal with rebound. Building on the foundation that the approach provides the paper recommends actions which provide a start toward deep societal change.