The accumulation of studies on outdoor recreation demand creates an opportunity to apply the growing science of reviewing research for purposes of benefit transfer. The process involves developing an understanding of the variables that explain the observed difference in estimates. This paper illustrates how the results of previous studies could be adjusted to develop some tentative estimates of nonmarket values for future policy analysis. Also, the evaluation of some potentially important variables should help improve statistical analysis and the allocation of resources to new studies. The challenge is to build each subsequent work on the knowledge gained from previous ones. In this experimental phase, there is a need to examine additional variables that might conceivably be more important than those considered in the past.