AbstractThe effectiveness of a national climate policy instrument is affected by the presence of policy interactions with other instruments that were not forecasted before its implementation. The problem can be confronted during the design of the instrument by determining forms, types and size of emerging interactions. This paper presents a systematic approach for evaluating the aggregate effect of interactions using a combination of three multi‐criteria methods, the analytical hierarchy process, the multi‐attribute utility theory and the Simple Multi‐Attribute Ranking Technique. The first is used for determining the weight coefficients for interaction forms and sub‐criteria. The other two are used for grading policy interactions under a set of three criteria and their sub‐criteria. The method is tested for two pairs of interactive instruments, IPPC and EU‐ETS, EU‐ETS and policies for the promotion of RES, within the Hellenic climate policy framework. Consistency and robustness tests are performed. Results are commented. Copyright © 2007 John Wiley & Sons, Ltd.