Non-compensatory preferences may form a significant component of individuals' values for non-market goods such as natural areas, especially in the context of a reduction in environmental quality. The widespread neglect of such preferences can result in erroneous estimates of changes in economic welfare. Non-market valuation using techniques such as contingent valuation therefore need to take into account the possibility that some individuals hold noncompensatory preferences. The formal structure of the lexicographic noncompensatory ordering is described, and the theoretical implications of an individual holding such preferences over some region of goods space is examined. A method for the empirical identification of non-compensatory preference orderings is outlined.