It has been stated that EIA influence on decisions is limited, and therefore there is a growing awareness of the developing needs of the EIA. According to the idea of assessment effectiveness, assessments are most likely to influence decision making when they are perceived credible (expertise), relevant (address key problems) and legitimate (assessment perceived as fair). Multi-Criteria Decision Analysis (MCDA) has many characteristics, such as the integration of diverse information and the handling of conflicting objectives, that make it very useful to support the entire EIA process. Thus far the MCDA cases in EIA processes have mainly focused on the ranking of alternatives instead of providing a framework for interactive and integrated assessment. In this article, we propose a systematic approach based on the practices and tools of MCDA for improving the relevancy and legitimacy of EIA. The approach described in this article is tested in a real-life EIA case of wind power park in Finland. One main difference of this new framework compared with the current EIA process in Finland is to focus more on the scoping phase in order to ensure that the most significant impacts of the project are included in the analysis. This helps to allocate resources on the important issues in the assessment and to avoid wasted effort on issues of little relevance. It also stimulates early collaboration between different parties of EIA.