The method of principal components is used to construct attractiveness indexes for existing and proposed wilderness areas in California. Rankings of areas based on this procedure are compared with those based on size and the subjective attractiveness index developed by the Forest Service. The derived indexes are then used to develop alternative opportunities variables that appear as explanatory variables in outdoor recreation demand functions. Results indicate that substantially better explanatory capacity can be achieved over alternative measures by including a competitive factor in the demand functions. The paper concludes by considering the substitution effects of introducing new wilderness areas into the system.