Governments regularly spend public funds to purchase environmental amenities. They might purchase land to add to the public estate, pay to fence stock out of endangered native forest, or offer stewardship payments as incentives to conservation. Governments also regularly introduce policies to achieve environmental goals, even though these policies impose costs on firms, households or farms. The basic decision rule, to maximise environmental benefits from a given budget, in all these cases is received wisdom within the economics profession. In the case of purchase of land to add to the public estate:Maximise environmental benefits by purchasing land in descending order of the ratio of benefit to cost until the budget is exhausted. More generally, funds should be allocated to individual activities within a programme in order of the decreasing ratio of benefits to costs until the budget is exhausted. This rule can be applied when benefits can be measured in any monetary or non-monetary quantitative index. In the case of conservation of vegetation, it can be applied relatively simply in the field when vegetation types and land values can be mapped jointly through GIS techniques. This simple decision rule is not always followed by government agencies that manage environmental programmes. Consider the protection of native vegetation, which is defined to include native forest, native woodland and native grassland. To meet international obligations to protect this kind of environment, most countries must involve private landholders in conservation because there are insufficient government reserves to meet the international commitments. Indeed, most countries have already introduced many policies to encourage private landholders to protect native vegetation on their forests and farms.