Environmental policy is characterised by complexity, in causes and effects, resulting in various combinations of policy instruments. However, evaluating these policy instrument mixes and assessing their effectiveness is difficult because of a lack of methodological approaches. This paper therefore proposes a methodology which comprises: (a) describing the underlying policy theory; (b) describing the policy instruments; (c) analysing goal attainment; and (d) evaluating effectiveness, focusing on coverage of points of intervention, steering power of policy instruments and coherence of the policy instruments mix. The methodology is illustrated with an evaluation of noise policy in the Netherlands – a typical complex policy domain in which a mix of policy instruments has been in place for decades, and thus provides a good empirical case.