Contingent valuation (CV) is a survey-based method frequently used for plac
ing monetary values on environmental goods and services not bought and sold
in the marketplace. CV is usually the only feasible method for including p
assive-use considerations in an economic analysis, a practice that has enge
ndered considerable controversy. The issue of what a CV study tries to valu
e is first addressed from the perspective of a policy-maker, and then the c
ontroversy over the inclusion of passive-use is taken up in more detail. Th
e major issues and positions taken in the technical debate over the use of
CV are summarized from a user's perspective. Key design and implementation
issues involved in undertaking a CV survey are examined, and the reader is
provided with a set of factors to examine in assessing the quality of a CV
study.