Compensating measures of consumers' surplus, i.e. "willingness to pay" for a preferred good and "willingness to accept compensation" and accept a less attractive good, are the appropriate indicators of value, unless redistribution toward the poor is an explicit project goal. In most cases, compensating measures, or acceptable approximations thereof, can be obtained without excessive difficulty. The conceptual bases of some currently used techniques of non-market valuation are examined, in order to identify the situations in which particular techniques are most appropriate. While valuation of non-market goods remains a challenging task, progress is being made in theory and application.