In the last decades, internationally comparative research has given great attention to problems of cross-cultural measurement and functional equivalence of constructs. Yet, the functional equivalence - or, more precisely, the cross cultural validity - of theoretical approaches has been discussed to a lesser degree. In this paper we test hypotheses on the relationship between national wealth, economic growth, postmaterialist values, and environmental concern using empirical data from the World Values Survey. In this context, Brechin's \"objective problems - subjective values\"-hypothesis (Brechin 1999) posits different sources of postmaterialism and environmental concern in developed and developing countries. Using multilevel regression models with cross-level interaction terms we show that the effect of postmaterialism on environmental concern indeed is moderated by national wealth: Whereas there is no effect in poorer countries, the relationship is substantially strong in wealthy countries. Therefore we argue that postmaterialist and environmental cognitions indeed form a coherent structure in developed countries, but should be considered
as isolated constructs in less developed nations.