This paper considers the modeling strategies that have been used to incorporate time in revealed and stated preference methods for valuing environmental resources. After reviewing a subset of the economic models for describing time as an input to household production; time in creating habits and persistence in demand for particular services of environmental resources, and time as offering an opportunity for future consumption, the overview suggests that time has been used as a complement in production or consumption to marketed goods in each of these frameworks. The paper suggests two possible alternatives. This structure along with further restrictions to preferences or technology implies that there are other strategies for using revealed preference data to measure the economic value of changes in environmental quality.