Theoretical issues arising in maximin and utilitarian programs are considered in order to shed light on the merits of various concepts of income and types of environmental accounting as guides for environmental policy. The accounting prices for sustaining an economy obey Hartwickʼs rule but are inconsistent with the principles of national accounting. Moreover, they would be formidably difficult to calculate. Green net national product is an approximate index of welfare in a utilitarian economy which maximises future discounted utility flows. These conclusions hold even if underlying conditions are non-autonomous.JEL Codes: Q3, E2