Based on an on-going research project called “Policy options for a resource efficient Europe” (POLFREE), this paper analyses potential policy instruments and their interdependencies in a policy mix for resource efficiency. It focuses on fundamental trade-offs in such a mix and identifies three generic challenges based on an empirical analysis of 27 specific instruments. The innovative aspect of the paper is to go beyond another long list of potential instruments or a mix of instruments, but to analyse them with regard to the theoretical requirements for coherence and consistency.