In this paper we establish how effectively EIA is currently utilised in the deployment of onshore and offshore wind energy in the United Kingdom (UK) and Germany. In this context, the quality of EIA documentation and the coverage of a range of key EIA aspects of 20 developments are evaluated. Furthermore, the impact of EIA on decision making is established, based on opinions of decision makers and other stakeholders. We find that whilst there are certain weaknesses, overall EIA information is central to decision making, and EIA is resulting in major project modifications. Our results differ from the findings of most previous studies which usually observed a moderate impact on decision making only.