To advise policy-makers about possible courses of action in the environmental domain, psychological science should employ a support system that allows for evidence-based decisions with respect to the three generic policy questions: what, where, and how. The key to such a system is a measurement instrument in which environmental motivation becomes tangible in individual actions. In this article, we provide empirical examples of such a decision support system in the environmental domain. It consists of (a) evidence about environmental motivation of persons, (b) evidence about motivation’s spatial distribution, (c) knowledge about the socio-cultural conditions that affect individuals when they translate motivation into action (i.e. structural information) , and (d) a forecast of the environmental impact—the concrete conservation potential of various behaviors.